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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
quant-ph/0607139 | Goro Oohata Dr. | Goro Oohata, Ryosuke Shimizu, Keiichi Edamatsu | Photon polarization entanglement induced by biexciton: experimental
evidence for violation of Bell's inequality | 4 pages, 5 figures | null | 10.1103/PhysRevLett.98.140503 | null | quant-ph | null | We have investigated the polarization entanglement between photon pairs
generated from a biexciton in a CuCl single crystal via resonant hyper
parametric scattering. The pulses of a high repetition pump are seen to provide
improved statistical accuracy and the ability to test Bell's inequality. Our
results clearly violate the inequality and thus manifest the quantum
entanglement and nonlocality of the photon pairs. We also analyzed the quantum
state of our photon pairs using quantum state tomography.
| [
{
"version": "v1",
"created": "Thu, 20 Jul 2006 15:20:04 GMT"
},
{
"version": "v2",
"created": "Fri, 21 Jul 2006 07:50:54 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Oohata",
"Goro",
""
],
[
"Shimizu",
"Ryosuke",
""
],
[
"Edamatsu",
"Keiichi",
""
]
]
|
quant-ph/0607140 | Marcus Aguiar de | Fernando Parisio and M. A. M. de Aguiar | A semiclassical trace formula for the canonical partition function of
one dimensional systems | 22 pages, 4 figures new section with applications to spin systems | Physica A 380 (2007) 211 | 10.1016/j.physa.2007.02.113 | null | quant-ph | null | We present a semiclassical trace formula for the canonical partition function
of arbitrary one-dimensional systems. The approximation is obtained via the
stationary exponent method applied to the phase-space integration of the
density operator in the coherent state representation. The formalism is valid
in the low temperature limit, presenting accurate results in this regime. As
illustrations we consider a quartic Hamiltonian that cannot be split into
kinetic and potential parts, and a system with two local minima. Applications
to spin systems are also presented.
| [
{
"version": "v1",
"created": "Thu, 20 Jul 2006 12:46:02 GMT"
},
{
"version": "v2",
"created": "Tue, 5 Sep 2006 10:46:43 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Parisio",
"Fernando",
""
],
[
"de Aguiar",
"M. A. M.",
""
]
]
|
quant-ph/0607141 | Tim Meyer | Tim Meyer, Hermann Kampermann, Matthias Kleinmann, and Dagmar Bruss | Finite key analysis for symmetric attacks in quantum key distribution | 9 pages, 5 figures | Phys. Rev. A 74, 042340 (2006) | 10.1103/PhysRevA.74.042340 | null | quant-ph | null | We introduce a constructive method to calculate the achievable secret key
rate for a generic class of quantum key distribution protocols, when only a
finite number n of signals is given. Our approach is applicable to all
scenarios in which the quantum state shared by Alice and Bob is known. In
particular, we consider the six state protocol with symmetric eavesdropping
attacks, and show that for a small number of signals, i.e. below the order of
10^4, the finite key rate differs significantly from the asymptotic value for n
approaching infinity. However, for larger n, a good approximation of the
asymptotic value is found. We also study secret key rates for protocols using
higher-dimensional quantum systems.
| [
{
"version": "v1",
"created": "Thu, 20 Jul 2006 13:03:48 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Meyer",
"Tim",
""
],
[
"Kampermann",
"Hermann",
""
],
[
"Kleinmann",
"Matthias",
""
],
[
"Bruss",
"Dagmar",
""
]
]
|
quant-ph/0607142 | Vincent Delaubert | Vincent Delaubert (LKB - Jussieu, ACQAO), Nicolas Treps (LKB -
Jussieu), Mikael Lassen (DTU), Charles C. Harb (ACQAO), Claude Fabre (LKB -
Jussieu), Ping Koy Lam (ACQAO), Hans A. Bachor (ACQAO) | TEM10 homodyne detection as an optimal small displacement and tilt
measurements scheme | 9 pages, 8 figures | null | 10.1103/PhysRevA.74.053823 | null | quant-ph | null | We report an experimental demonstration of optimal measurements of small
displacement and tilt of a Gaussian beam - two conjugate variables - involving
a homodyne detection with a TEM10 local oscillator. We verify that the standard
split detection is only 64% efficient. We also show a displacement measurement
beyond the quantum noise limit, using a squeezed vacuum TEM10 mode within the
input beam.
| [
{
"version": "v1",
"created": "Thu, 20 Jul 2006 15:08:31 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Delaubert",
"Vincent",
"",
"LKB - Jussieu, ACQAO"
],
[
"Treps",
"Nicolas",
"",
"LKB -\n Jussieu"
],
[
"Lassen",
"Mikael",
"",
"DTU"
],
[
"Harb",
"Charles C.",
"",
"ACQAO"
],
[
"Fabre",
"Claude",
"",
"LKB -\n Jussieu"
],
[
"Lam",
"Ping Koy",
"",
"ACQAO"
],
[
"Bachor",
"Hans A.",
"",
"ACQAO"
]
]
|
quant-ph/0607143 | Gonzalo Abal | G. Abal, R. Donangelo, H. Fort | Conditional Quantum Walk and Iterated Quantum Games | Revtex 4, 6 pages, 3 figures. Expanded version with one more figure
and updated references. Abstract was rewritten | Physica A, 387, pp 5326-5332, 2008. | 10.1016/j.physa.2008.04.036 | null | quant-ph | null | Iterated bipartite quantum games are implemented in terms of the
discrete-time quantum walk on the line. Our proposal allows for conditional
strategies, as two rational agents make a choice from a restricted set of
two-qubit unitary operations. Several frequently used classical strategies give
rise to families of corresponding quantum strategies. A quantum version of the
Prisoner's Dilemma in which both players use mixed strategies is presented as a
specific example. Since there are now quantum walk physical implementations at
a proof-of principle stage, this connection may represent a step towards the
experimental realization of quantum games.
| [
{
"version": "v1",
"created": "Thu, 20 Jul 2006 15:26:05 GMT"
},
{
"version": "v2",
"created": "Wed, 1 Nov 2006 18:17:18 GMT"
},
{
"version": "v3",
"created": "Fri, 16 Mar 2007 19:44:53 GMT"
}
]
| 2008-07-31T00:00:00 | [
[
"Abal",
"G.",
""
],
[
"Donangelo",
"R.",
""
],
[
"Fort",
"H.",
""
]
]
|
quant-ph/0607144 | Xijia Miao | Xijia Miao | The basic principles to construct a generalized state-locking pulse
field and simulate efficiently the reversible and unitary halting protocol of
a universal quantum computer | 107 pages. A minor modification | null | null | null | quant-ph | null | It has been shown (Arxiv: quant-ph/0507236) that a universal quantum computer
could be powerful enough to solve efficiently the quantum search problem, and
the reversible and unitary halting protocol based on the state-locking pulse
field is the key component to construct the efficient quantum search processes,
while the state-locking pulse field is the key component to generate the
reversible and unitary halting protocol. In this paper the reversible and
unitary halting protocol and the generalized state-locking pulse field have
been extensively investigated theoretically. The basic principles to construct
the state-locking pulse field and design the reversible and unitary halting
protocol are studied in detail. A generalized state-locking pulse field is
generally dependent upon the time and space variables. It could be a sequence
of time- and space-dependent electromagnetic pulse fields and could also
contain the time- and space-dependent potential fields. Thus, the reversible
and unitary halting protocol built up out of the state-locking pulse field
generally consists of a sequence of time- and space-dependent unitary evolution
processes. It is shown how the quantum control process is constructed to
simulate efficiently the reversible and unitary halting protocol. An improved
subspace-reduction quantum program and circuit based on the reversible and
unitary halting protocol is proposed as the key component to construct further
an efficient quantum search process. A simple atomic physical system that is an
atomic ion or a neutral atom in the double-well potential field is proposed to
show how the state-locking pulse field is generated and how to implement the
reversible and unitary halting protocol.
| [
{
"version": "v1",
"created": "Thu, 20 Jul 2006 16:13:49 GMT"
},
{
"version": "v2",
"created": "Mon, 18 Sep 2006 02:09:13 GMT"
},
{
"version": "v3",
"created": "Mon, 27 Nov 2006 00:32:28 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Miao",
"Xijia",
""
]
]
|
quant-ph/0607145 | Alioscia Hamma | Alioscia Hamma, Daniel A. Lidar (Center for Quantum Information
Science & Technology, USC) | Adiabatic Preparation of Topological Order | 4 pages, one figure. v4: includes new error estimates for the
adiabatic evolution | Phys. Rev. Lett. 100, 030502 (2008) | 10.1103/PhysRevLett.100.030502 | null | quant-ph cond-mat.str-el | null | Topological order characterizes those phases of matter that defy a
description in terms of symmetry and cannot be distinguished in terms local
order parameters. This type of order plays a key role in the theory of the
fractional quantum Hall effect, as well as in topological quantum information
processing. Here we show that a system of n spins forming a lattice on a
Riemann surface can undergo a second order quantum phase transition between a
spin-polarized phase and a string-net condensed phase. This is an example of a
phase transition between magnetic and topological order. We furthermore show
how to prepare the topologically ordered phase through adiabatic evolution in a
time that is upper bounded by O(\sqrt{n}). This provides a physically plausible
method for constructing a topological quantum memory. We discuss applications
to topological and adiabatic quantum computing.
| [
{
"version": "v1",
"created": "Fri, 21 Jul 2006 19:53:47 GMT"
},
{
"version": "v2",
"created": "Fri, 28 Jul 2006 18:04:00 GMT"
},
{
"version": "v3",
"created": "Mon, 11 Dec 2006 20:09:08 GMT"
},
{
"version": "v4",
"created": "Sat, 13 Oct 2007 01:16:17 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Hamma",
"Alioscia",
"",
"Center for Quantum Information\n Science & Technology, USC"
],
[
"Lidar",
"Daniel A.",
"",
"Center for Quantum Information\n Science & Technology, USC"
]
]
|
quant-ph/0607146 | Alejandro Romanelli | A. Romanelli, A. Auyuanet, R. Siri, V. Micenmacher | Sub-ballistic behaviour of the Quantum Kicked Rotor | 9 pages, 3 figures, to appear in Phys. Lett. A | Phys Lett. A 365, 200 (2007) | 10.1016/j.physleta.2007.01.015 | null | quant-ph | null | We study the resonances of the quantum kicked rotor subjected to an
excitation that follows an aperiodic Fibonacci prescription. In such a case the
secondary resonances show a sub-ballistic behaviour like the quantum walk with
the same aperiodic prescription for the coin. The principal resonances maintain
the well-known ballistic behaviour. Then the parallelism previusly established
between the kicked rotor and the generalized quantum walk is retained only with
the secondary resonances.
| [
{
"version": "v1",
"created": "Thu, 20 Jul 2006 22:07:37 GMT"
},
{
"version": "v2",
"created": "Fri, 2 Feb 2007 21:55:09 GMT"
}
]
| 2008-02-18T00:00:00 | [
[
"Romanelli",
"A.",
""
],
[
"Auyuanet",
"A.",
""
],
[
"Siri",
"R.",
""
],
[
"Micenmacher",
"V.",
""
]
]
|
quant-ph/0607147 | Charles Santori | Charles Santori, Philippe Tamarat, Philipp Neumann, Jorg Wrachtrup,
David Fattal, Raymond G. Beausoleil, James Rabeau, Paolo Olivero, Andrew
Greentree, Steven Prawer, Fedor Jelezko, Philip Hemmer | Coherent Population Trapping of Single Spins in Diamond Under Optical
Excitation | minor corrections | Phys. Rev. Lett. 97, 247401 (2006) | 10.1103/PhysRevLett.97.247401 | null | quant-ph cond-mat.mtrl-sci | null | Coherent population trapping is demonstrated in single nitrogen-vacancy
centers in diamond under optical excitation. For sufficient excitation power,
the fluorescence intensity drops almost to the background level when the laser
modulation frequency matches the 2.88 GHz splitting of the ground states. The
results are well described theoretically by a four-level model, allowing the
relative transition strengths to be determined for individual centers. The
results show that all-optical control of single spins is possible in diamond.
| [
{
"version": "v1",
"created": "Fri, 21 Jul 2006 01:20:26 GMT"
},
{
"version": "v2",
"created": "Tue, 1 Aug 2006 01:25:28 GMT"
},
{
"version": "v3",
"created": "Sat, 9 Dec 2006 21:21:48 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Santori",
"Charles",
""
],
[
"Tamarat",
"Philippe",
""
],
[
"Neumann",
"Philipp",
""
],
[
"Wrachtrup",
"Jorg",
""
],
[
"Fattal",
"David",
""
],
[
"Beausoleil",
"Raymond G.",
""
],
[
"Rabeau",
"James",
""
],
[
"Olivero",
"Paolo",
""
],
[
"Greentree",
"Andrew",
""
],
[
"Prawer",
"Steven",
""
],
[
"Jelezko",
"Fedor",
""
],
[
"Hemmer",
"Philip",
""
]
]
|
quant-ph/0607148 | Paul Bourdon | P. S. Bourdon and H. T. Williams | Sharp probability estimates for Shor's order-finding algorithm | 33 pages, 2 figures. Revised: minor errors corrected, exposition
improved, submitted version | null | null | null | quant-ph | null | Let N be a (large positive integer, let b > 1 be an integer relatively prime
to N, and let r be the order of b modulo N. Finally, let QC be a quantum
computer whose input register has the size specified in Shor's original
description of his order-finding algorithm. We prove that when Shor's algorithm
is implemented on QC, then the probability P of obtaining a (nontrivial)
divisor of r exceeds 0.7 whenever N exceeds 2^{11}-1 and r exceeds 39, and we
establish that 0.7736 is an asymptotic lower bound for P. When N is not a power
of an odd prime, Gerjuoy has shown that P exceeds 90 percent for N and r
sufficiently large. We give easily checked conditions on N and r for this 90
percent threshold to hold, and we establish an asymptotic lower bound for P of
(2/Pi) Si(4Pi), about .9499, in this situation. More generally, for any
nonnegative integer q, we show that when QC(q) is a quantum computer whose
input register has q more qubits than does QC, and Shor's algorithm is run on
QC(q), then an asymptotic lower bound on P is (2/Pi) Si(2^(q+2) Pi) (if N is
not a power of an odd prime). Our arguments are elementary and our lower bounds
on P are carefully justified.
| [
{
"version": "v1",
"created": "Fri, 21 Jul 2006 07:00:29 GMT"
},
{
"version": "v2",
"created": "Fri, 4 Aug 2006 15:02:50 GMT"
},
{
"version": "v3",
"created": "Mon, 4 Sep 2006 00:52:24 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Bourdon",
"P. S.",
""
],
[
"Williams",
"H. T.",
""
]
]
|
quant-ph/0607149 | Jaromir Fiurasek | A. Cernoch, L. Bartuskova, J. Soubusta, M. Jezek, J. Fiurasek, M.
Dusek | Experimental phase-covariant cloning of polarization states of single
photons | 5 pages, 4 figures, REVTeX4 | Phys. Rev. A 74, 042327 (2006). | 10.1103/PhysRevA.74.042327 | null | quant-ph | null | The experimental realization of optimal symmetric phase-covariant 1->2
cloning of qubit states is presented. The qubits are represented by
polarization states of photons generated by spontaneous parametric
down-conversion. The experiment is based on the interference of two photons on
a custom-made beam splitter with different splitting ratios for vertical and
horizontal polarization components. From the measured data we have estimated
the implemented cloning transformation using the maximum-likelihood method. The
result shows that the realized transformation is very close to the ideal one
and the map fidelity reaches 94%.
| [
{
"version": "v1",
"created": "Fri, 21 Jul 2006 13:13:46 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Cernoch",
"A.",
""
],
[
"Bartuskova",
"L.",
""
],
[
"Soubusta",
"J.",
""
],
[
"Jezek",
"M.",
""
],
[
"Fiurasek",
"J.",
""
],
[
"Dusek",
"M.",
""
]
]
|
quant-ph/0607150 | Michael Fleischhauer | J\"urgen K\"astel, Michael Fleischhauer | Comment on: "Electromagnetically induced left-handedness in optically
excited four-level atomic media" | 1 page, one figure, comment on Phys. Rev. Lett. {\bf 96}, 053601
(2006) | null | 10.1103/PhysRevLett.98.069301 | null | quant-ph | null | We discuss the recent proposal by Thommen and Mandel (Phys. Rev. Lett. {\bf
96}, 053601 (2006)) for electromagnetically induced negative refraction.
Although the main conclusion of the paper -- the possibility to achieve
negative refraction in an experimentally accessible atomic scheme -- remains
valid, we show that the weak-excitation approximation used is invalid in the
parameter regime studied and leads to quantitatively incorrect predictions. We
show that negative refraction is always accompanied by absorption rather than
by gain, and that the maximum value of the refraction-absorption ratio is of
order unity.
| [
{
"version": "v1",
"created": "Fri, 21 Jul 2006 11:59:12 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Kästel",
"Jürgen",
""
],
[
"Fleischhauer",
"Michael",
""
]
]
|
quant-ph/0607151 | Ben Rudiak-Gould | Ben Rudiak-Gould | The sum-over-histories formulation of quantum computing | Draft, no references. Currently under revision | null | null | null | quant-ph | null | Since Deutsch (1985), quantum computers have been modeled exclusively in the
language of state vectors and the Schroedinger equation. We present a
complementary view of quantum circuits inspired by the path integral formalism
of quantum mechanics, and examine its application to some simple textbook
problems.
| [
{
"version": "v1",
"created": "Fri, 21 Jul 2006 12:41:58 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rudiak-Gould",
"Ben",
""
]
]
|
quant-ph/0607152 | Shasanka Mohan Roy | S. M. Roy (University of York, United Kingdom, and Tata Institute of
Fundamental Research, Mumbai, India) and Samuel L. Braunstein (University of
York, United Kingdom) | Exponentially Enhanced Quantum Metrology | 4 pages, 1 postscript figure ; typos corrected | null | 10.1103/PhysRevLett.100.220501 | null | quant-ph | null | We show that when a suitable entanglement generating unitary operator
depending on a parameter is applied on N qubits in parallel, and an appropriate
observable is measured, a precision of order 2 raised to the power (-N) in
estimating the parameter may be achieved. This exponentially improves the
precision achievable in classical and in quantum non-entangling parallel
strategies. We propose a quantum-optics model of laser light interacting with
an N-qubit system, say a polyatomic molecule, via a generalized Jaynes-Cummings
interaction which, in principle, could achieve the exponentially enhanced
precision.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 18:27:12 GMT"
}
]
| 2013-05-29T00:00:00 | [
[
"Roy",
"S. M.",
"",
"University of York, United Kingdom, and Tata Institute of\n Fundamental Research, Mumbai, India"
],
[
"Braunstein",
"Samuel L.",
"",
"University of\n York, United Kingdom"
]
]
|
quant-ph/0607153 | Ru-Fen Liu | Ru-Fen Liu and Chia-Chu Chen | Role of Bell Singlet State in the Suppression of Disentanglement | 5 pages, 2 figures, accepted by Phys. Rev. A | Phys. Rev. A 74, 024102 (2006) | 10.1103/PhysRevA.74.024102 | null | quant-ph | null | The stability of entanglement of two atoms in a cavity is analyzed in this
work. By studying the general Werner states we clarify the role of Bell-singlet
state in the problem of suppression of disentanglement due to spontaneous
emission. It is also shown explicitly that the final amount of entanglement
depends on the initial ingredients of the Bell-singlet state.
| [
{
"version": "v1",
"created": "Sat, 22 Jul 2006 03:01:38 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Liu",
"Ru-Fen",
""
],
[
"Chen",
"Chia-Chu",
""
]
]
|
quant-ph/0607154 | Andreas Fring | Carla Figueira de Morisson Faria and Andreas Fring | Isospectral Hamiltonians from Moyal products | 10 pages, to appear special issue Czech. J. Phys | Czech. J. Phys. 56 (2006) 899 | 10.1007/s10582-006-0386-x | null | quant-ph | null | Recently Scholtz and Geyer proposed a very efficient method to compute metric
operators for non-Hermitian Hamiltonians from Moyal products. We develop these
ideas further and suggest to use a more symmetrical definition for the Moyal
products, because they lead to simpler differential equations. In addition, we
demonstrate how to use this approach to determine the Hermitian counterpart for
a Pseudo-Hermitian Hamiltonian. We illustrate our suggestions with the
explicitly solvable example of the -x^4-potential and the ubiquitous harmonic
oscillator in a complex cubic potential.
| [
{
"version": "v1",
"created": "Sat, 22 Jul 2006 15:32:09 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Faria",
"Carla Figueira de Morisson",
""
],
[
"Fring",
"Andreas",
""
]
]
|
quant-ph/0607155 | Eduardo Novais | E. Novais, Eduardo R. Mucciolo, Harold U. Baranger | Resilient Quantum Computation in Correlated Environments: A Quantum
Phase Transition Perspective | 4.1 pages, minor correction and an improved discussion of Eqs. (4)
and (14) | Phys. Rev. Lett. 98, 040501 (2007) | 10.1103/PhysRevLett.98.040501 | null | quant-ph cond-mat.stat-mech | null | We analyze the problem of a quantum computer in a correlated environment
protected from decoherence by QEC using a perturbative renormalization group
approach. The scaling equation obtained reflects the competition between the
dimension of the computer and the scaling dimension of the correlations. For an
irrelevant flow, the error probability is reduced to a stochastic form for long
time and/or large number of qubits; thus, the traditional derivation of the
threshold theorem holds for these error models. In this way, the ``threshold
theorem'' of quantum computing is rephrased as a dimensional criterion.
| [
{
"version": "v1",
"created": "Sat, 22 Jul 2006 18:51:51 GMT"
},
{
"version": "v2",
"created": "Wed, 15 Nov 2006 15:28:21 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Novais",
"E.",
""
],
[
"Mucciolo",
"Eduardo R.",
""
],
[
"Baranger",
"Harold U.",
""
]
]
|
quant-ph/0607156 | Mark Oxborrow | Mark Oxborrow | Ex-house 2D finite-element simulation of the whispering-gallery modes of
arbitrarily shaped axisymmetric electromagnetic resonators | 21 pages, 8 figures, 4 tables; submitted to IEEE Transactions on
Microwave Theory and Techniques. Corrected 20th March 2007 | null | null | null | quant-ph | null | It is described, explicitly, how a popular, commercially-available software
package for solving partial-differential-equations (PDEs), as based on the
finite-element method (FEM), can be configured to calculate the frequencies and
fields of the whispering-gallery (WG) modes of axisymmetric dielectric
resonators. The approach is traceable; it exploits the PDE-solver's ability to
accept the definition of solutions to Maxwell's equations in so-called `weak
form'. Associated expressions and methods for estimating a WG mode's volume,
filling factor(s) and, in the case of closed(open) resonators, its wall
(radiation) loss, are provided. As no transverse approxi-mation is imposed, the
approach remains accurate even for so-called quasi-TM and -TE modes of low,
finite azimuthal mode order. The approach's generality and utility are
demonstrated by modeling several non-trivial structures: (i)two different
optical microcavities [one toroidal made of silica, the other an AlGaAs
microdisk]; (ii) a 3rd-order microwave Bragg cavity containing alumina layers
(iii) two different cryogenic sapphire X-band microwave resonators. By fitting
one of the latter to a set of measured resonance frequencies, the dielectric
constants of sapphire at liquid-helium temperature have been estimated.
| [
{
"version": "v1",
"created": "Sun, 23 Jul 2006 05:40:17 GMT"
},
{
"version": "v2",
"created": "Tue, 20 Mar 2007 15:24:42 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Oxborrow",
"Mark",
""
]
]
|
quant-ph/0607157 | Simen Ellingsen | Simen A. Ellingsen | Casimir attraction in multilayered plane parallel magnetodielectric
systems | 13 pages, 6 figures. Version 2: Updated contact details. Minor
changes and corrections | J.Phys. A: Math. Theor. 40 (2007) 1951-1961 | 10.1088/1751-8113/40/9/003 | null | quant-ph | null | A powerful procedure is presented for calculating the Casimir attraction
between plane parallel multilayers made up of homogeneous regions with
arbitrary magnetic and dielectric properties by use of the Minkowski
energy-momentum tensor. The theory is applied to numerous geometries and shown
to reproduce a number of results obtained by other authors. Although the
various pieces of theory drawn upon are well known, the relative ease with
which the Casimir force density in even complex planar structures may be
calculated, appears not to be widely appreciated, and no single paper to the
author's knowledge renders explicitly the procedure demonstrated herein.
Results may be seen as an important building block in the settling of issues of
fundamental interest, such as the long-standing dispute over the thermal
behaviour of the Casimir force or the question of what is the correct stress
tensor to apply, a discussion re-quickened by the newly suggested alternative
theory due to Raabe and Welsch.
| [
{
"version": "v1",
"created": "Sun, 23 Jul 2006 13:04:14 GMT"
},
{
"version": "v2",
"created": "Tue, 26 Sep 2006 12:52:32 GMT"
}
]
| 2015-06-26T00:00:00 | [
[
"Ellingsen",
"Simen A.",
""
]
]
|
quant-ph/0607158 | Omar Mustafa | Omar Mustafa and S.Habib Mazharimousavi | Ordering ambiguity revisited via position dependent mass pseudo-momentum
operators | 10 pages, no figures, revised/expanded, mathematical presentations in
section 2 (Especially, the typological Errors in Eqs.(9)-(12))are now
corrected. To appear in the Int. J. Theor. Phys | Int. J. Theor. Phys. 46, 1786 (2007) | 10.1007/s10773-006-9311-0 | null | quant-ph | null | Ordering ambiguity associated with the von Roos position dependent mass (PDM)
Hamiltonian is considered. An affine locally scaled first order differential
introduced, in Eq.(9), as a PDM-pseudo-momentum operator. Upon intertwining our
Hamiltonian, which is the sum of the square of this operator and the potential
function, with the von Roos d-dimensional PDM-Hamiltonian, we observed that the
so-called von Roos ambiguity parameters are strictly determined, but not
necessarily unique. Our new ambiguity parameters' setting is subjected to
Dutra's and Almeida's [11] reliability test and classified as good ordering.
| [
{
"version": "v1",
"created": "Sun, 23 Jul 2006 19:34:35 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Sep 2006 07:20:01 GMT"
},
{
"version": "v3",
"created": "Thu, 26 Oct 2006 15:46:33 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Mustafa",
"Omar",
""
],
[
"Mazharimousavi",
"S. Habib",
""
]
]
|
quant-ph/0607159 | Takashi Yamamoto | Takashi Yamamoto, Ryoji Nagase, Junichi Shimamura, Sahin Kaya Ozdemir,
Masato Koashi, and Nobuyuki Imoto | Experimental ancilla-assisted qubit transmission against correlated
noise using quantum parity checking | 8 pages, 4 figures; published in New J. Phys. and selected in IOP
Select | New J. Phys. 9 (2007) 191 | 10.1088/1367-2630/9/6/191 | null | quant-ph | null | We report the experimental demonstration of a transmission scheme of photonic
qubits over unstabilized optical fibers, which has the plug-and-play feature as
well as the ability to transmit any state of a qubit, regardless of whether it
is known, unknown, or entangled to other systems. A high fidelity to the
noiseless quantum channel was achieved by adding an ancilla photon after the
signal photon within the correlation time of the fiber noise and by performing
quantum parity checking. Simplicity, maintenance-free feature and robustness
against path-length mismatches among the nodes make our scheme suitable for
multi-user quantum communication networks.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 02:14:02 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Jul 2007 14:05:06 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Yamamoto",
"Takashi",
""
],
[
"Nagase",
"Ryoji",
""
],
[
"Shimamura",
"Junichi",
""
],
[
"Ozdemir",
"Sahin Kaya",
""
],
[
"Koashi",
"Masato",
""
],
[
"Imoto",
"Nobuyuki",
""
]
]
|
quant-ph/0607160 | Rodney Van Meter | Rodney Van Meter, W.J. Munro, Kae Nemoto, Kohei M. Itoh | Arithmetic on a Distributed-Memory Quantum Multicomputer | 24 pages, 10 figures, ACM transactions format. Extended version of
Int. Symp. on Comp. Architecture (ISCA) paper; v2, correct one circuit error,
numerous small changes for clarity, add references | ACM J. Emerging Technologies in Computing Systems, 3(4), Jan. 2008 | 10.1145/1324177.1324179 | null | quant-ph | null | We evaluate the performance of quantum arithmetic algorithms run on a
distributed quantum computer (a quantum multicomputer). We vary the node
capacity and I/O capabilities, and the network topology. The tradeoff of
choosing between gates executed remotely, through ``teleported gates'' on
entangled pairs of qubits (telegate), versus exchanging the relevant qubits via
quantum teleportation, then executing the algorithm using local gates
(teledata), is examined. We show that the teledata approach performs better,
and that carry-ripple adders perform well when the teleportation block is
decomposed so that the key quantum operations can be parallelized. A node size
of only a few logical qubits performs adequately provided that the nodes have
two transceiver qubits. A linear network topology performs acceptably for a
broad range of system sizes and performance parameters. We therefore recommend
pursuing small, high-I/O bandwidth nodes and a simple network. Such a machine
will run Shor's algorithm for factoring large numbers efficiently.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 04:16:27 GMT"
},
{
"version": "v2",
"created": "Tue, 6 Mar 2007 08:01:34 GMT"
}
]
| 2008-02-12T00:00:00 | [
[
"Van Meter",
"Rodney",
""
],
[
"Munro",
"W. J.",
""
],
[
"Nemoto",
"Kae",
""
],
[
"Itoh",
"Kohei M.",
""
]
]
|
quant-ph/0607161 | Ressa Said | R S Said, M R B Wahiddin, and B A Umarov | Generation of Three-Qubit Entangled W-State by Nonlinear Optical State
Truncation | 7 pages, 2 figure | J. Phys. B: At. Mol. Opt. Phys. 39 (2006) 1269-1274 | 10.1088/0953-4075/39/6/001 | null | quant-ph | null | We propose an alternative scheme to generate W state via optical state
truncation using quantum scissors. In particular, these states may be generated
through three-mode optical state truncation in a Kerr nonlinear coupler. The
more general three-qubit state may be also produced if the system is driven by
external classical fields.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 06:16:49 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Said",
"R S",
""
],
[
"Wahiddin",
"M R B",
""
],
[
"Umarov",
"B A",
""
]
]
|
quant-ph/0607162 | Aurel Gabris | Aurel Gabris, Girish S. Agarwal | Quantum teleportation with pair-coherent states | Based on talks at the QIP workshop in 6th Joint Conference on
Mathematics and Computer Science, Pecs, 12-15 July 2006; and Quantum 2006 -
Workshop ad memoriam Carlo Novero, Turin. v2: Added reference to give credit
to L. Vaidman | Int. Journal of Quant. Inf. 5, 17-22 (2007) | 10.1142/S0219749907002475 | null | quant-ph | null | Recently it has been argued that all presently performed continuous variable
quantum teleportation experiments could be explained using a local hidden
variable theory. In this paper we study a modification of the original protocol
which requires a fully quantum mechanical explanation even when coherent states
are teleported. Our calculations of the fidelity of teleportation using a
pair-coherent state under ideal conditions suggests that fidelity above the
required limit of 1/2 may be achievable in an experiment also.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 13:29:01 GMT"
},
{
"version": "v2",
"created": "Thu, 3 Aug 2006 16:56:26 GMT"
}
]
| 2007-08-04T00:00:00 | [
[
"Gabris",
"Aurel",
""
],
[
"Agarwal",
"Girish S.",
""
]
]
|
quant-ph/0607163 | Michael Reimpell | O. G\"uhne, M. Reimpell, R.F. Werner | Estimating entanglement measures in experiments | 4 pages, 1 figure, v2: final version | Phys. Rev. Lett. 98, 110502 (2007) | 10.1103/PhysRevLett.98.110502 | null | quant-ph | null | We present a method to estimate entanglement measures in experiments. We show
how a lower bound on a generic entanglement measure can be derived from the
measured expectation values of any finite collection of entanglement witnesses.
Hence witness measurements are given a quantitative meaning without the need of
further experimental data. We apply our results to a recent multi-photon
experiment [M. Bourennane et al., Phys. Rev. Lett. 92, 087902 (2004)], giving
bounds on the entanglement of formation and the geometric measure of
entanglement in this experiment.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 13:52:36 GMT"
},
{
"version": "v2",
"created": "Mon, 12 Mar 2007 18:58:27 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Gühne",
"O.",
""
],
[
"Reimpell",
"M.",
""
],
[
"Werner",
"R. F.",
""
]
]
|
quant-ph/0607164 | Mohamad Ali Jafarizadeh | M. A. Jafarizadeh, M. Rezaeen, S.Ahadpour | Generalized qudit Choi maps | 22 pages | null | 10.1103/PhysRevA.74.042335 | null | quant-ph | null | Following the linear programming prescription of Ref. \cite{PRA72}, the
$d\otimes d$ Bell diagonal entanglement witnesses are provided. By using
Jamiolkowski isomorphism, it is shown that the corresponding positive maps are
the generalized qudit Choi maps. Also by manipulating particular $d\otimes d$
Bell diagonal separable states and constructing corresponding bound entangled
states, it is shown that thus obtained $d\otimes d$ BDEW's (consequently qudit
Choi maps) are non-decomposable in certain range of their parameters.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 13:58:33 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Jafarizadeh",
"M. A.",
""
],
[
"Rezaeen",
"M.",
""
],
[
"Ahadpour",
"S.",
""
]
]
|
quant-ph/0607165 | Peter Morgan | Peter Morgan | Models of measurement for quantum fields and for classical continuous
random fields | This is a submission for the Proceedings of the Vaxjo Conference on
the Foundations of Probability and Physics-4. Comments very welcome | AIPConf.Proc.889:187-197,2007 | 10.1063/1.2713457 | null | quant-ph | null | A quantum field model for an experiment describes thermal fluctuations
explicitly and quantum fluctuations implicitly, whereas a comparable continuous
random field model would describe both thermal and quantum fluctuations
explicitly. An ideal classical measurement does not affect the results of later
measurements, in contrast to ideal quantum measurements, but we can describe
the consequences of the thermal and quantum fluctuations of classically
non-ideal measurement apparatuses explicitly. Some details of continuous random
fields and of Bell inequalities for random fields will be discussed.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 14:06:18 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Morgan",
"Peter",
""
]
]
|
quant-ph/0607166 | Dmitri Maslov | D. Maslov, D. M. Miller, and G. W. Dueck | Techniques for the Synthesis of Reversible Toffoli Networks | 20 pages, 5 figures | ACM Transactions on Design Automation of Electronic Systems 12(4),
Article 42, September 2007 | 10.1145/1278349.1278355 | null | quant-ph | null | This paper presents novel techniques for the synthesis of reversible networks
of Toffoli gates, as well as improvements to previous methods. Gate count and
technology oriented cost metrics are used. Our synthesis techniques are
independent of the cost metrics. Two new iterative synthesis procedure
employing Reed-Muller spectra are introduced and shown to complement earlier
synthesis approaches. The template simplification suggested in earlier work is
enhanced through introduction of a faster and more efficient template
application algorithm, updated (shorter) classification of the templates, and
presentation of the new templates of sizes 7 and 9. A novel ``resynthesis''
approach is introduced wherein a sequence of gates is chosen from a network,
and the reversible specification it realizes is resynthesized as an independent
problem in hopes of reducing the network cost. Empirical results are presented
to show that the methods are effective both in terms of the realization of all
3x3 reversible functions and larger reversible benchmark specifications.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 18:38:27 GMT"
}
]
| 2011-08-01T00:00:00 | [
[
"Maslov",
"D.",
""
],
[
"Miller",
"D. M.",
""
],
[
"Dueck",
"G. W.",
""
]
]
|
quant-ph/0607167 | Fernando Brandao | Jens Eisert, Fernando G.S.L. Brandao, Koenraad M.R. Audenaert | Quantitative entanglement witnesses | 10 pages RevTeX, 1 figure, replaced with published version | New J. Phys. 9, 46 (2007) | 10.1088/1367-2630/9/3/046 | null | quant-ph cond-mat.other | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Entanglement witnesses provide tools to detect entanglement in experimental
situations without the need of having full tomographic knowledge about the
state. If one estimates in an experiment an expectation value smaller than
zero, one can directly infer that the state has been entangled, or specifically
multi-partite entangled, in the first place. In this article, we emphasize that
all these tests - based on the very same data - give rise to quantitative
estimates in terms of entanglement measures: "If a test is strongly violated,
one can also infer that the state was quantitatively very much entangled". We
consider various measures of entanglement, including the negativity, the
entanglement of formation, and the robustness of entanglement, in the bipartite
and multipartite setting. As examples, we discuss several experiments in the
context of quantum state preparation that have recently been performed.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 16:56:40 GMT"
},
{
"version": "v2",
"created": "Thu, 10 Aug 2006 19:25:48 GMT"
},
{
"version": "v3",
"created": "Fri, 2 Mar 2007 21:01:24 GMT"
},
{
"version": "v4",
"created": "Tue, 27 Aug 2013 07:31:53 GMT"
}
]
| 2013-08-28T00:00:00 | [
[
"Eisert",
"Jens",
""
],
[
"Brandao",
"Fernando G. S. L.",
""
],
[
"Audenaert",
"Koenraad M. R.",
""
]
]
|
quant-ph/0607168 | R. de la Madrid | R. de la Madrid | Description of resonances within the rigged Hilbert space | 23 pages; written version of the five-lecture course delivered at the
2006 Summer School of CINVESTAV, Mexico City, July 2006 | AIPConf.Proc.885:3-25,2007 | 10.1063/1.2563170 | null | quant-ph hep-th math-ph math.MP | null | The spectrum of a quantum system has in general bound, scattering and
resonant parts. The Hilbert space includes only the bound and scattering
spectra, and discards the resonances. One must therefore enlarge the Hilbert
space to a rigged Hilbert space, within which the physical bound, scattering
and resonance spectra are included on the same footing. In these lectures, I
will explain how this is done.
| [
{
"version": "v1",
"created": "Mon, 24 Jul 2006 21:28:20 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"de la Madrid",
"R.",
""
]
]
|
quant-ph/0607169 | David Miller Dr | D. J. Miller | Quantum mechanics as a consistency condition on initial and final
boundary conditions | 13 pages, 2 figures, based on a talk at the conference: Time-symmetry
in Quantum Mechanics, Sydney, Australia, 23-26 July 2005 | null | null | null | quant-ph | null | If the block universe view is correct, the future and the past have similar
status and one would expect physical theories to involve final as well as
initial boundary conditions. A plausible consistency condition between the
initial and final boundary conditions in non-relativistic quantum mechanics
leads to the idea that the properties of macroscopic quantum systems,
relevantly measuring instruments, are uniquely determined by the boundary
conditions. An important element in reaching that conclusion is that
preparations and measurements belong in a special class because they involve
many subsystems, at least some of which do not form superpositions of their
physical properties before the boundary conditions are imposed. It is suggested
that the primary role of the formalism of standard quantum mechanics is to
provide the consistency condition on the boundary conditions rather than the
properties of quantum systems. Expressions are proposed for assigning a set of
(unmeasured) physical properties to a quantum system at all times. The physical
properties avoid the logical inconsistencies implied by the no-go theorems
because they are assigned differently from standard quantum mechanics. Since
measurement outcomes are determined by the boundary conditions, they help
determine, rather than are determined by, the physical properties of quantum
systems.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 01:57:27 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Miller",
"D. J.",
""
]
]
|
quant-ph/0607170 | Fedor Jelezko | Ph. Tamarat, T. Gaebel, J. R. Rabeau, M. Khan, A. D. Greentree, H.
Wilson, L. C. L. Hollenberg, S. Prawer, P. Hemmer, F. Jelezko, J. Wrachtrup | Stark shift control of single optical centers in diamond | 13 pages, 4 figures | Phys. Rev. Lett. 97 (8): Art. No. 083002 (2006) | 10.1103/PhysRevLett.97.083002 | null | quant-ph | null | Lifetime limited optical excitation lines of single nitrogen vacancy (NV)
defect centers in diamond have been observed at liquid helium temperature. They
display unprecedented spectral stability over many seconds and excitation
cycles. Spectral tuning of the spin selective optical resonances was performed
via the application of an external electric field (i.e. the Stark shift). A
rich variety of Stark shifts were observed including linear as well as
quadratic components. The ability to tune the excitation lines of single NV
centers has potential applications in quantum information processing.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 06:42:14 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Tamarat",
"Ph.",
""
],
[
"Gaebel",
"T.",
""
],
[
"Rabeau",
"J. R.",
""
],
[
"Khan",
"M.",
""
],
[
"Greentree",
"A. D.",
""
],
[
"Wilson",
"H.",
""
],
[
"Hollenberg",
"L. C. L.",
""
],
[
"Prawer",
"S.",
""
],
[
"Hemmer",
"P.",
""
],
[
"Jelezko",
"F.",
""
],
[
"Wrachtrup",
"J.",
""
]
]
|
quant-ph/0607171 | Kristian Helmerson | M. F. Andersen, C. Ryu, Pierre Clade, V. Natarajan, A. Vaziri, K.
Helmerson, W. D. Phillips | Quantized Rotation of Atoms From Photons with Orbital Angular Momentum | New version, 4 pages and 3 figures, accepted for publication in
Physical Review Letters | null | 10.1103/PhysRevLett.97.170406 | null | quant-ph | null | We demonstrate the coherent transfer of the orbital angular momentum of a
photon to an atom in quantized units of hbar, using a 2-photon stimulated Raman
process with Laguerre-Gaussian beams to generate an atomic vortex state in a
Bose-Einstein condensate of sodium atoms. We show that the process is coherent
by creating superpositions of different vortex states, where the relative phase
between the states is determined by the relative phases of the optical fields.
Furthermore, we create vortices of charge 2 by transferring to each atom the
orbital angular momentum of two photons.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 17:03:05 GMT"
},
{
"version": "v2",
"created": "Fri, 20 Oct 2006 21:35:35 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Andersen",
"M. F.",
""
],
[
"Ryu",
"C.",
""
],
[
"Clade",
"Pierre",
""
],
[
"Natarajan",
"V.",
""
],
[
"Vaziri",
"A.",
""
],
[
"Helmerson",
"K.",
""
],
[
"Phillips",
"W. D.",
""
]
]
|
quant-ph/0607172 | Andrei Khrennikov | Guillaume Adenier and Andrei Khrennikov | Anomalies in experimental data for the EPR-Bohm experiment: Are both
classical and quantum mechanics wrong? | Presented in talks at conferences: "Foundations of Probability and
Physics-4" (Vaxjo, Sweden, June 2006), "Quantum Probability" (Greifswald,
Germany, March 2006 and Nottingham, UK, July 2006), "Quantum Structures
Association" (Malta, July 2006) | null | null | Report from MSI, N 060712 | quant-ph | null | We analyze anomalies in data to test the violation of Bell's inequality for
the EPR-Bohm experiment. We found that the experimental correlations for photon
polarization have an intriguing property. In the experimental data there are
visible non-negligible deviations of probabilities $P_{++}^{\rm{exp}}(\alpha,
\beta), P_{+-}^{\rm{exp}}(\alpha, \beta), P_{-+}^{\rm{exp}}(\alpha, \beta),
P_{--}^{\rm{exp}}(\alpha, \beta) $ from the predictions of quantum mechanics,
namely, $P_{++}(\alpha, \beta)=P_{--}(\alpha, \beta)=
{1/2}\cos^2(\alpha-\beta)$ and $P_{+-}=P_{-+}(\alpha,
\beta)={1/2}\sin^2(\alpha-\beta).$ However, in some mysterious way those
deviations compensate each other and finally the correlation
$E^{\rm{exp}}(\alpha, \beta)= P_{++}^{\rm{exp}}(\alpha, \beta)-
P_{+-}^{\rm{exp}}(\alpha, \beta)- P_{-+}^{\rm{exp}}(\alpha, \beta)+
P_{--}^{\rm{exp}}(\alpha, \beta)$ is in the complete agreement with the
QM-prediction, namely, $E(\alpha, \beta)= P_{++}(\alpha, \beta)- P_{+-}(\alpha,
\beta)- P_{-+}(\alpha, \beta)+ P_{--}(\alpha, \beta)= \cos 2(\alpha-\beta).$
Therefore such anomalies play no role in the Bell's inequality framework.
Nevertheless, other linear combinations of experimental probabilities do not
have such a compensation property. There can be found non-negligible deviations
from predictions of quantum mechanics. Thus neither classical nor quantum model
can pass the whole family of statistical tests given by all possible linear
combinations of the EPR-Bohm probabilities. Does it mean that both models are
wrong?
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 10:02:35 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Adenier",
"Guillaume",
""
],
[
"Khrennikov",
"Andrei",
""
]
]
|
quant-ph/0607173 | Iordanis Kerenidis | Iordanis Kerenidis, Ran Raz | The one-way communication complexity of the Boolean Hidden Matching
Problem | null | null | null | null | quant-ph cs.CC | null | We give a tight lower bound of Omega(\sqrt{n}) for the randomized one-way
communication complexity of the Boolean Hidden Matching Problem [BJK04]. Since
there is a quantum one-way communication complexity protocol of O(\log n)
qubits for this problem, we obtain an exponential separation of quantum and
classical one-way communication complexity for partial functions. A similar
result was independently obtained by Gavinsky, Kempe, de Wolf [GKdW06]. Our
lower bound is obtained by Fourier analysis, using the Fourier coefficients
inequality of Kahn Kalai and Linial [KKL88].
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 10:07:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Kerenidis",
"Iordanis",
""
],
[
"Raz",
"Ran",
""
]
]
|
quant-ph/0607174 | Julia Kempe | Dmytro Gavinsky, Julia Kempe, Ronald de Wolf | Exponential Separation of Quantum and Classical One-Way Communication
Complexity for a Boolean Function | 8 pages, no figures | null | null | null | quant-ph cs.CC | null | We give an exponential separation between one-way quantum and classical
communication complexity for a Boolean function. Earlier such a separation was
known only for a relation. A very similar result was obtained earlier but
independently by Kerenidis and Raz [KR06]. Our version of the result gives an
example in the bounded storage model of cryptography, where the key is secure
if the adversary has a certain amount of classical storage, but is completely
insecure if he has a similar amount of quantum storage.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 10:08:07 GMT"
}
]
| 2022-03-29T00:00:00 | [
[
"Gavinsky",
"Dmytro",
""
],
[
"Kempe",
"Julia",
""
],
[
"de Wolf",
"Ronald",
""
]
]
|
quant-ph/0607175 | Xue Peng | P. Xue, and Y.F. Xiao | Universal quantum computation in deocoherence-free subspace with neutral
atoms | 4 pages,2 figures. Final version as published in PRL | Phys. Rev. Lett 97, 140501 (2006) | 10.1103/PhysRevLett.97.140501 | null | quant-ph | null | We show how realistic cavity-assisted interaction between neutral atoms and
coherent optical pulses, and measurement techniques, combined with optical
transportation of atoms, allow for a universal set of quantum gates acting on
decoherence-free subspace (DFS) in deterministic way. The logical qubits are
immunized to the dominant source of decoherece--dephasing; while, the
influences of additional errors are shown by numerical simulations. We analyze
the performance and stability of all required operations and emphasize that all
techniques we use are feasible with current experimental technology.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 14:52:58 GMT"
},
{
"version": "v2",
"created": "Wed, 9 Aug 2006 13:18:11 GMT"
},
{
"version": "v3",
"created": "Sun, 17 Sep 2006 17:54:01 GMT"
}
]
| 2011-01-14T00:00:00 | [
[
"Xue",
"P.",
""
],
[
"Xiao",
"Y. F.",
""
]
]
|
quant-ph/0607176 | Przemyslaw Koscik | Przemyslaw Koscik, Anna Okopinska | Quasi-exact solutions for two interacting electrons in two-dimensional
anisotropic dots | 11 pages, 4 figures | J.Phys .A:Math.Theor.40(2007)1045-1055 | 10.1088/1751-8113/40/5/012 | null | quant-ph cond-mat.mtrl-sci cond-mat.str-el math-ph math.MP | null | We present an analysis of the two-dimensional Schrodinger equation for two
electrons interacting via Coulombic force and confined in an anizotropic
harmonic potential. The separable case of wy = 2wx is studied particularly
carefully. The closed-form expressions for bound-state energies and the
corresponding eigenfunctions are found at some particular values of wx. For
highly-accurate determination of energy levels at other values of wx, we apply
an efficient scheme based on the Frobenius expansion.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 11:37:47 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Dec 2006 21:45:18 GMT"
},
{
"version": "v3",
"created": "Wed, 28 Feb 2007 07:53:42 GMT"
}
]
| 2017-07-17T00:00:00 | [
[
"Koscik",
"Przemyslaw",
""
],
[
"Okopinska",
"Anna",
""
]
]
|
quant-ph/0607177 | Danna Rosenberg | P. A. Hiskett, D. Rosenberg, C. G. Peterson, R. J. Hughes, S. Nam, A.
E. Lita, A. J. Miller and J. E. Nordholt | Long-distance quantum key distribution in optical fiber | 7 pages, 4 figures | null | 10.1088/1367-2630/8/9/193 | LA-UR-06-3212 | quant-ph | null | Use of low-noise detectors can both increase the secret bit rate of
long-distance quantum key distribution (QKD) and dramatically extend the length
of a fibre optic link over which secure key can be distributed. Previous work
has demonstrated use of ultra-low-noise transition-edge sensors (TESs) in a QKD
system with transmission over 50 km. In this work, we demonstrate the potential
of the TESs by successfully generating error-corrected, privacy-amplified key
over 148.7 km of dark optical fibre at a mean photon number mu = 0.1, or 184.6
km of dark optical fibre at a mean photon number of 0.5. We have also exchanged
secret key over 67.5 km that is secure against powerful photon-number-splitting
attacks.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 17:58:58 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Hiskett",
"P. A.",
""
],
[
"Rosenberg",
"D.",
""
],
[
"Peterson",
"C. G.",
""
],
[
"Hughes",
"R. J.",
""
],
[
"Nam",
"S.",
""
],
[
"Lita",
"A. E.",
""
],
[
"Miller",
"A. J.",
""
],
[
"Nordholt",
"J. E.",
""
]
]
|
quant-ph/0607178 | Andre Stegner | A. R. Stegner, C. Boehme, H. Huebl, M. Stutzmann, K. Lips and M. S.
Brandt | Electrical detection of 31P spin quantum states | null | null | 10.1038/nphys465 | null | quant-ph | null | In recent years, a variety of solid-state qubits has been realized, including
quantum dots, superconducting tunnel junctions and point defects. Due to its
potential compatibility with existing microelectronics, the proposal by Kane
based on phosphorus donors in Si has also been pursued intensively. A key issue
of this concept is the readout of the P quantum state. While electrical
measurements of magnetic resonance have been performed on single spins, the
statistical nature of these experiments based on random telegraph noise
measurements has impeded the readout of single spin states. In this letter, we
demonstrate the measurement of the spin state of P donor electrons in silicon
and the observation of Rabi flops by purely electric means, accomplished by
coherent manipulation of spin-dependent charge carrier recombination between
the P donor and paramagnetic localized states at the Si/SiO2 interface via
pulsed electrically detected magnetic resonance. The electron spin information
is shown to be coupled through the hyperfine interaction with the P nucleus,
which demonstrates the feasibility of a recombination-based readout of nuclear
spins.
| [
{
"version": "v1",
"created": "Tue, 25 Jul 2006 20:21:40 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Stegner",
"A. R.",
""
],
[
"Boehme",
"C.",
""
],
[
"Huebl",
"H.",
""
],
[
"Stutzmann",
"M.",
""
],
[
"Lips",
"K.",
""
],
[
"Brandt",
"M. S.",
""
]
]
|
quant-ph/0607179 | Han Chuen Lim | Han Chuen Lim, Dexiang Wang, Takuo Tanemura, Kazuhiro Katoh, Kazuro
Kikuchi | All-Fiber Source of Polarization-Entangled Photon Pairs Based on a Novel
Birefringence Compensated Scheme | Presented at LEOS Summer Topical Meetings, Quebec City, Canada, 17-19
July, 2006, paper TuB2.4 | null | null | null | quant-ph | null | We propose a new all-fiber source of polarization-entangled photon pairs for
quantum communications. Fiber birefringence is compensated using Faraday
rotator mirror, resulting in enhanced stability against random polarization
drifts compared to existing schemes.
| [
{
"version": "v1",
"created": "Wed, 26 Jul 2006 05:26:35 GMT"
},
{
"version": "v2",
"created": "Mon, 23 Oct 2006 02:30:55 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Lim",
"Han Chuen",
""
],
[
"Wang",
"Dexiang",
""
],
[
"Tanemura",
"Takuo",
""
],
[
"Katoh",
"Kazuhiro",
""
],
[
"Kikuchi",
"Kazuro",
""
]
]
|
quant-ph/0607180 | Guo-Yong Xiang | Guo-Yong Xiang, Jian Li, and Guang-Can Guo | Interference of quantum channels in single photon interferometer | 3 pages, 5 figures | null | null | null | quant-ph | null | We experimently demonstrate the interference of dephasing quantum channel
using single photon Mach-Zender interferometer. We extract the information
inaccessible to the technology of quantum tomography. Further, We introduce the
application of our results in quantum key distribution.
| [
{
"version": "v1",
"created": "Wed, 26 Jul 2006 09:14:07 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Xiang",
"Guo-Yong",
""
],
[
"Li",
"Jian",
""
],
[
"Guo",
"Guang-Can",
""
]
]
|
quant-ph/0607181 | N. L. Harshman | N. L. Harshman, S. Wickramasekara | Galilean and Dynamical Invariance of Entanglement in Particle Scattering | 4 pages, no figures; v.3 has typos corrected, a new reference, and a
revised conclusion | PRL 98 (2007), 080406 | 10.1103/PhysRevLett.98.080406 | null | quant-ph | null | Particle systems admit a variety of tensor product structures (TPSs)
depending on the algebra of observables chosen for analysis. Global symmetry
transformations and dynamical transformations may be resolved into local
unitary operators with respect to certain TPSs and not with respect to others.
Symmetry-invariant and dynamical-invariant TPSs are defined and various notions
of entanglement are considered for scattering states.
| [
{
"version": "v1",
"created": "Wed, 26 Jul 2006 09:54:27 GMT"
},
{
"version": "v2",
"created": "Fri, 29 Sep 2006 19:15:59 GMT"
},
{
"version": "v3",
"created": "Mon, 23 Oct 2006 20:38:53 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Harshman",
"N. L.",
""
],
[
"Wickramasekara",
"S.",
""
]
]
|
quant-ph/0607182 | Rupert Ursin | R. Ursin, F. Tiefenbacher, T. Schmitt-Manderbach, H. Weier, T.
Scheidl, M. Lindenthal, B. Blauensteiner, T. Jennewein, J. Perdigues, P.
Trojek, B. Oemer, M. Fuerst, M. Meyenburg, J. Rarity, Z. Sodnik, C. Barbieri,
H. Weinfurter, A. Zeilinger | Free-Space distribution of entanglement and single photons over 144 km | 10 pages including 2 figures and 1 table, Corrected typos | Nature Physics 3, 481 - 486 (2007) | 10.1038/nphys629 | null | quant-ph | null | Quantum Entanglement is the essence of quantum physics and inspires
fundamental questions about the principles of nature. Moreover it is also the
basis for emerging technologies of quantum information processing such as
quantum cryptography, quantum teleportation and quantum computation. Bell's
discovery, that correlations measured on entangled quantum systems are at
variance with a local realistic picture led to a flurry of experiments
confirming the quantum predictions. However, it is still experimentally
undecided whether quantum entanglement can survive global distances, as
predicted by quantum theory. Here we report the violation of the
Clauser-Horne-Shimony-Holt (CHSH) inequality measured by two observers
separated by 144 km between the Canary Islands of La Palma and Tenerife via an
optical free-space link using the Optical Ground Station (OGS) of the European
Space Agency (ESA). Furthermore we used the entangled pairs to generate a
quantum cryptographic key under experimental conditions and constraints
characteristic for a Space-to-ground experiment. The distance in our experiment
exceeds all previous free-space experiments by more than one order of magnitude
and exploits the limit for ground-based free-space communication; significantly
longer distances can only be reached using air- or space-based platforms. The
range achieved thereby demonstrates the feasibility of quantum communication in
space, involving satellites or the International Space Station (ISS).
| [
{
"version": "v1",
"created": "Wed, 26 Jul 2006 14:29:14 GMT"
},
{
"version": "v2",
"created": "Thu, 27 Jul 2006 07:47:40 GMT"
}
]
| 2007-08-30T00:00:00 | [
[
"Ursin",
"R.",
""
],
[
"Tiefenbacher",
"F.",
""
],
[
"Schmitt-Manderbach",
"T.",
""
],
[
"Weier",
"H.",
""
],
[
"Scheidl",
"T.",
""
],
[
"Lindenthal",
"M.",
""
],
[
"Blauensteiner",
"B.",
""
],
[
"Jennewein",
"T.",
""
],
[
"Perdigues",
"J.",
""
],
[
"Trojek",
"P.",
""
],
[
"Oemer",
"B.",
""
],
[
"Fuerst",
"M.",
""
],
[
"Meyenburg",
"M.",
""
],
[
"Rarity",
"J.",
""
],
[
"Sodnik",
"Z.",
""
],
[
"Barbieri",
"C.",
""
],
[
"Weinfurter",
"H.",
""
],
[
"Zeilinger",
"A.",
""
]
]
|
quant-ph/0607183 | Jin-Shi Xu | Jin-Shi Xu, Chuan-Feng Li and Guang-Can Guo | Generation of a High-Visibility Four-Photon Entangled State and
Realization of a Four-Party Quantum Communication Complexity Scenario | REVTEX 4.0, 4 pages, 4 figures, 1 table | Phys. Rev. A 74, 052311 (2006) | 10.1103/PhysRevA.74.052311 | null | quant-ph | null | We obtain a four-photon polarization-entangled state with a visibility as
high as (95.35\pm 0.45)% directly from a single down-conversion source. A
success probability of (81.54\pm 1.38)% is observed by applying this entangled
state to realize a four-party quantum communication complexity scenario (QCCS),
which comfortably surpass the classical limit of 50%. As a comparison, two
Einstein-Podolsky-Rosen (EPR) pairs are shown to implement the scenario with a
success probability of (73.89\pm 1.33)%. This four-photon state can be used to
fulfill decoherence-free quantum information processing and other advanced
quantum communication schemes.
| [
{
"version": "v1",
"created": "Wed, 26 Jul 2006 14:37:06 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Xu",
"Jin-Shi",
""
],
[
"Li",
"Chuan-Feng",
""
],
[
"Guo",
"Guang-Can",
""
]
]
|
quant-ph/0607184 | Segio Barreiro sergiob | S. Barreiro, J.W.R. Tabosa, H. Failache and A. Lezama | Spectroscopic observation of the rotational Doppler effect | Submited to Physical Review Letter | null | 10.1103/PhysRevLett.97.113601 | null | quant-ph | null | We report on the first spectroscopic observation of the rotational Doppler
shift associated with light beams carrying orbital angular momentum. The effect
is evidenced as the broadening of a Hanle/EIT coherence resonance on Rb vapor
when the two incident Laguerre-Gaussian laser beams have opposite topological
charges. The observations closely agree with theoretical predictions.
| [
{
"version": "v1",
"created": "Wed, 26 Jul 2006 14:58:08 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Barreiro",
"S.",
""
],
[
"Tabosa",
"J. W. R.",
""
],
[
"Failache",
"H.",
""
],
[
"Lezama",
"A.",
""
]
]
|
quant-ph/0607185 | Rubens Ramos Viana | Joao Batista Rosa Silva and Rubens Viana Ramos | Implementations of quantum and classical gates with linear optical
devices and photon number quantum non-demolition measurement for polarization
encoded qubits | 14 Pages 8 Figures | null | null | null | quant-ph | null | Aiming the construction of quantum computers and quantum communication
systems based on optical devices, in this work we present possible
implementations of quantum and classical CNOTs gates, as well an optical setup
for generation and distribution of bipartite entangled states, using linear
optical devices and photon number quantum non-demolition measurement.
| [
{
"version": "v1",
"created": "Wed, 26 Jul 2006 16:05:12 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Silva",
"Joao Batista Rosa",
""
],
[
"Ramos",
"Rubens Viana",
""
]
]
|
quant-ph/0607186 | Danna Rosenberg | Danna Rosenberg, Jim W. Harrington, Patrick R. Rice, Philip A.
Hiskett, Charles G. Peterson, Richard J. Hughes, Adriana E. Lita, Sae Woo Nam
and Jane E. Nordholt | Long distance decoy state quantum key distribution in optical fiber | 4 pages, 3 figures | Phys. Rev. Lett. 98 010503 (2007) | 10.1103/PhysRevLett.98.010503 | LA-UR-06-5220 | quant-ph | null | The theoretical existence of photon-number-splitting attacks creates a
security loophole for most quantum key distribution (QKD) demonstrations that
use a highly attenuated laser source. Using ultra-low-noise, high-efficiency
transition-edge sensor photodetectors, we have implemented the first version of
a decoy-state protocol that incorporates finite statistics without the use of
Gaussian approximations in a one-way QKD system, enabling the creation of
secure keys immune to photon-number-splitting attacks and highly resistant to
Trojan horse attacks over 107 km of optical fiber.
| [
{
"version": "v1",
"created": "Wed, 26 Jul 2006 23:34:43 GMT"
},
{
"version": "v2",
"created": "Wed, 2 May 2007 21:32:58 GMT"
}
]
| 2007-08-01T00:00:00 | [
[
"Rosenberg",
"Danna",
""
],
[
"Harrington",
"Jim W.",
""
],
[
"Rice",
"Patrick R.",
""
],
[
"Hiskett",
"Philip A.",
""
],
[
"Peterson",
"Charles G.",
""
],
[
"Hughes",
"Richard J.",
""
],
[
"Lita",
"Adriana E.",
""
],
[
"Nam",
"Sae Woo",
""
],
[
"Nordholt",
"Jane E.",
""
]
]
|
quant-ph/0607187 | Zhang Zhanjun Dr. | Zhang-yin Wang and Zhan-jun Zhang | Three-party qutrit-state sharing | 7 pages | null | 10.1140/epjd/e2006-00215-y | null | quant-ph | null | A three-party scheme for securely sharing an arbitrary unknown single-qutrit
state is presented. Using a general Greenberger-Horne-Zeilinger (GHZ) state as
the quantum channel among the three parties, the quantum information (i.e., the
qutrit state) from the sender can be split in such a way that the information
can be recovered if and only if both receivers collaborate. Moreover, the
generation of the scheme to multi-party case is also sketched.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 02:44:15 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Wang",
"Zhang-yin",
""
],
[
"Zhang",
"Zhan-jun",
""
]
]
|
quant-ph/0607188 | C.M. Chandrashekar | C.M. Chandrashekar, R. Srikanth and Subhashish Banerjee | Symmetries and noise in quantum walk | 19 pages, 24 figures : V3 - Revised version to appear in Phys. Rev.
A. - new section on quantum walk in a cycle included | Phys. Rev. A . 76, 022316 (2007) | 10.1103/PhysRevA.76.022316 | null | quant-ph cond-mat.other | null | We study some discrete symmetries of unbiased (Hadamard) and biased quantum
walk on a line, which are shown to hold even when the quantum walker is
subjected to environmental effects. The noise models considered in order to
account for these effects are the phase flip, bit flip and generalized
amplitude damping channels. The numerical solutions are obtained by evolving
the density matrix, but the persistence of the symmetries in the presence of
noise is proved using the quantum trajectories approach. We also briefly extend
these studies to quantum walk on a cycle. These investigations can be relevant
to the implementation of quantum walks in various known physical systems. We
discuss the implementation in the case of NMR quantum information processor and
ultra cold atoms.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 03:18:41 GMT"
},
{
"version": "v2",
"created": "Mon, 5 Feb 2007 14:59:24 GMT"
},
{
"version": "v3",
"created": "Fri, 27 Jul 2007 16:30:31 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Chandrashekar",
"C. M.",
""
],
[
"Srikanth",
"R.",
""
],
[
"Banerjee",
"Subhashish",
""
]
]
|
quant-ph/0607189 | Wang Zhiwei | Zhi-Wei Wang, Jian Li, Yun-Feng Huang, Yong-Sheng Zhang, Xi-Feng Ren,
Pei Zhang, Guang-Can Guo | Linear Optical Implemention of a Quantum Network for Quantum Estimation | 8 pages,4 figures. Revised edition | null | null | null | quant-ph | null | We present a scheme for simulating the quantum network of quantum estimation
proposed by A. K. Ekert et al. [Phys. Rev. Lett. 88, 217901 (2002)]. We
experimentally implement the scheme with linear optical elements. We perform
overlap measurements of two single-qubit states and entanglement-witness
measurements of some two-qubit states. In addition, it can also be used for
entanglement quantification for some kinds of states. From the other
perspective, we physically realize the positive but not completely positive
map, transposition.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 03:41:18 GMT"
},
{
"version": "v2",
"created": "Mon, 14 Aug 2006 07:46:55 GMT"
},
{
"version": "v3",
"created": "Wed, 27 Sep 2006 02:29:06 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Wang",
"Zhi-Wei",
""
],
[
"Li",
"Jian",
""
],
[
"Huang",
"Yun-Feng",
""
],
[
"Zhang",
"Yong-Sheng",
""
],
[
"Ren",
"Xi-Feng",
""
],
[
"Zhang",
"Pei",
""
],
[
"Guo",
"Guang-Can",
""
]
]
|
quant-ph/0607190 | Che-Ming Li | Che-Ming Li, Li-Yi Hsu, Wei-Yang Lin, Yueh-Nan Chen, Der-San Chuu, and
Tobias Brandes | Correlation criteria for Bell type inequalities and entanglement
detection | 4 pages | null | null | null | quant-ph | null | We provide a novel criterion for identifying quantum correlation, which
allows us to find connections between Bell type inequalities, entanglement
detection, and correlation. We utilize the criterion to construct witness
operators that can detect genuine multi-qubit entanglement with fewer local
measurements. The connection between identifications of quantum correlation and
Mermin's inequality is discussed. Detection of genuine four-level tripartite
entanglement with two local measurement settings is shown in the same manner.
Further, through the criterion of quantum correlation, we derive a new Bell
inequality for arbitrary high-dimensional bipartite systems, which requires
fewer analyses of the measured outcomes.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 08:00:40 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Li",
"Che-Ming",
""
],
[
"Hsu",
"Li-Yi",
""
],
[
"Lin",
"Wei-Yang",
""
],
[
"Chen",
"Yueh-Nan",
""
],
[
"Chuu",
"Der-San",
""
],
[
"Brandes",
"Tobias",
""
]
]
|
quant-ph/0607191 | Ivette Fuentes-Guridi | I. Fuentes-Schuller, P. Barberis-Blostein | A family of many-body models which are exactly solvable analytically | 4 pages, 2 figures; I. F-S published previously under Fuentes-Guridi | J.Phys.A40:F601-F608,2007 | 10.1088/1751-8113/40/27/F04 | null | quant-ph cond-mat.mes-hall nucl-th | null | We present a family of many-body models which are exactly solvable
analytically. The models are an extended n-body interaction
Lipkin-Meshkov-Glick model which considers spin-flip terms which are associated
with the interaction of an external classical field which coherently
manipulates the state of the system in order to, for example, process quantum
information. The models also describe a two-mode Bose-Einstein condensate with
a Josephson-type interaction which includes n-particle elastic and inelastic
collisions. One of the models corresponds to the canonical two-mode
Bose-Einstein Hamitonian plus a term which we argue must be considered in the
description of the two-mode condensate. Intriguingly, this extra term allows
for an exact and analytical solution of the two-particle collision two-mode BEC
problem. Our results open up an arena to study many-body system properties
analytically.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 10:23:45 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Fuentes-Schuller",
"I.",
""
],
[
"Barberis-Blostein",
"P.",
""
]
]
|
quant-ph/0607192 | David Atkinson | S.M. Roy, D. Atkinson, G. Auberson, G. Mahoux, V. Singh | Joint Probabilities Reproducing Three EPR Experiments On Two Qubits | Typo corrected in abstract | null | 10.1142/S0217732307024061 | null | quant-ph | null | An eight parameter family of the most general nonnegative quadruple
probabilities is constructed for EPR-Bohm-Aharonov experiments when only 3
pairs of analyser settings are used. It is a simultaneous representation of 3
Bohr-incompatible experimental configurations valid for arbitrary quantum
states.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 14:40:35 GMT"
},
{
"version": "v2",
"created": "Mon, 31 Jul 2006 11:52:21 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Roy",
"S. M.",
""
],
[
"Atkinson",
"D.",
""
],
[
"Auberson",
"G.",
""
],
[
"Mahoux",
"G.",
""
],
[
"Singh",
"V.",
""
]
]
|
quant-ph/0607193 | A. R. P. Rau | I. Mazumdar, A. R. P. Rau, and V. S. Bhasin | Efimov states and their Fano resonances in a neutron-rich nucleus | 4 double-column pages, 3 figures | Phys.Rev.Lett. 97 (2006) 062503 | 10.1103/PhysRevLett.97.062503 | null | quant-ph nucl-th | null | Asymmetric resonances in elastic n+$^{19}$C scattering are attributed to
Efimov states of such neutron-rich nuclei, that is, three-body bound states of
the n+n+$^{18}$C system when none of the pairs is bound or some of them only
weakly bound. By fitting to the general resonance shape described by Fano, we
extract resonance position, width, and the "Fano profile index". While Efimov
states have been discussed extensively in many areas of physics, there is only
one very recent experimental observation in trimers of cesium atoms. The
conjunction that we present of the Efimov and Fano phenomena may lead to
experimental realization in nuclei.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 15:49:55 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Mazumdar",
"I.",
""
],
[
"Rau",
"A. R. P.",
""
],
[
"Bhasin",
"V. S.",
""
]
]
|
quant-ph/0607194 | Yu-Ao Chen | Yu-Ao Chen, Tao Yang, An-Ning Zhang, Zhi Zhao, Adan Cabello and
Jian-Wei Pan | Experimental Violation of Bell Inequality beyond Cirel'son's Bound | 4 pages, 3 figures | Phys. Rev. Lett. 97, 170408 (2006) | 10.1103/PhysRevLett.97.170408 | null | quant-ph | null | The correlations between two qubits belonging to a three-qubit system can
violate the Clauser-Horne-Shimony-Holt-Bell inequality beyond Cirel'son's bound
[A. Cabello, Phys. Rev. Lett. 88, 060403 (2002)]. We experimentally demonstrate
such a violation by 7 standard deviations by using a three-photon
polarization-entangled Greenberger-Horne-Zeilinger state produced by Type-II
spontaneous parametric down-conversion. In addition, using part of our results,
we obtain a violation of the Mermin inequality by 39 standard deviations.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 16:03:23 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Chen",
"Yu-Ao",
""
],
[
"Yang",
"Tao",
""
],
[
"Zhang",
"An-Ning",
""
],
[
"Zhao",
"Zhi",
""
],
[
"Cabello",
"Adan",
""
],
[
"Pan",
"Jian-Wei",
""
]
]
|
quant-ph/0607195 | Julio de Vicente | Julio I. de Vicente | Separability criteria based on the Bloch representation of density
matrices | 17 pages, no figures; Section 4.2 improved; final version: minor
changes, added references, to appear in QIC | Quantum Inf. Comput. 7, 624 (2007) | 10.26421/QIC7.7-5 | null | quant-ph | null | We study the separability of bipartite quantum systems in arbitrary
dimensions using the Bloch representation of their density matrix. This
approach enables us to find an alternative characterization of the separability
problem, from which we derive a necessary condition and sufficient conditions
for separability. For a certain class of states the necessary condition and a
sufficient condition turn out to be equivalent, therefore yielding a necessary
and sufficient condition. The proofs of the sufficient conditions are
constructive, thus providing decompositions in pure product states for the
states that satisfy them. We provide examples that show the ability of these
conditions to detect entanglement. In particular, the necessary condition is
proved to be strong enough to detect bound entangled states.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 16:40:52 GMT"
},
{
"version": "v2",
"created": "Fri, 8 Sep 2006 18:38:02 GMT"
},
{
"version": "v3",
"created": "Fri, 2 Mar 2007 11:27:55 GMT"
}
]
| 2024-12-05T00:00:00 | [
[
"de Vicente",
"Julio I.",
""
]
]
|
quant-ph/0607196 | Andrei Khrennikov | Elio Conte, Andrei Khrennikov, Joseph P. Zbilut | The transition from ontic potentiality to actualization of states in
quantum mechanical approach to reality: The Proof of a Mathematical Theorem
to Support It | null | null | null | null | quant-ph | null | It is given a preliminary discussion on the ontic nature of quantum states to
be intended as potentialities and on the central role of spin to be considered
as the basic essence of quantum mechanical reality. The possible fundamental
role of potentialities and of spin is evidenced in the framework of physical as
well as of biological reality. After such preliminary deepening, using a
quantum like scheme delineated on the basis of an algebraic structure, it is
given for the first time mathematical demonstration of the transition from
potentiality of states to their actualization as basic mechanism of our
reality.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 16:49:01 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Conte",
"Elio",
""
],
[
"Khrennikov",
"Andrei",
""
],
[
"Zbilut",
"Joseph P.",
""
]
]
|
quant-ph/0607197 | Almut Beige | M. Trupke, J. Metz, A. Beige, and E. A. Hinds | Towards quantum computing with single atoms and optical cavities on atom
chips | 14 pages, 6 figures | J. Mod. Opt. 54, 1639 (2007). | 10.1080/09500340600934240 | null | quant-ph | null | We report on recent developments in the integration of optical
microresonators into atom chips and describe some fabrication and
implementation challenges. We also review theoretical proposals for quantum
computing with single atoms based on the observation of photons leaking through
the cavity mirrors. The use of measurements to generate entanglement can result
in simpler, more robust and scalable quantum computing architectures. Indeed,
we show that quantum computing with atom-cavity systems is feasible even in the
presence of relatively large spontaneous decay rates and finite photon detector
efficiencies.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 17:10:38 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Trupke",
"M.",
""
],
[
"Metz",
"J.",
""
],
[
"Beige",
"A.",
""
],
[
"Hinds",
"E. A.",
""
]
]
|
quant-ph/0607198 | Erik Sjoqvist | Erik Sj\"oqvist, David Kult, and Johan {\AA}berg | Manifestations of quantum holonomy in interferometry | Some changes, journal reference added | Phys. Rev. A 74, 062101 (2006) | 10.1103/PhysRevA.74.062101 | null | quant-ph | null | Abelian and non-Abelian geometric phases, known as quantum holonomies, have
attracted considerable attention in the past. Here, we show that it is possible
to associate nonequivalent holonomies to discrete sequences of subspaces in a
Hilbert space. We consider two such holonomies that arise naturally in
interferometer settings. For sequences approximating smooth paths in the base
(Grassmann) manifold, these holonomies both approach the standard holonomy. In
the one-dimensional case the two types of holonomies are Abelian and coincide
with Pancharatnam's geometric phase factor. The theory is illustrated with a
model example of projective measurements involving angular momentum coherent
states.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 17:49:15 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Dec 2006 09:23:58 GMT"
}
]
| 2016-08-16T00:00:00 | [
[
"Sjöqvist",
"Erik",
""
],
[
"Kult",
"David",
""
],
[
"Åberg",
"Johan",
""
]
]
|
quant-ph/0607199 | Alex Retzker | A. Retzker and M.B. Plenio | Fast cooling of trapped ions using the dynamical Stark shift gate | 4 pages 5 figures | New J. Phys. 9 (2007) 279 | 10.1063/1.2836210 | null | quant-ph | null | A laser cooling scheme for trapped ions is presented which is based on the
fast dynamical Stark shift gate, described in [Jonathan etal, PRA 62, 042307].
Since this cooling method does not contain an off resonant carrier transition,
low final temperatures are achieved even in traveling wave light field. The
proposed method may operate in either pulsed or continuous mode and is also
suitable for ion traps using microwave addressing in strong magnetic field
gradients.
| [
{
"version": "v1",
"created": "Thu, 27 Jul 2006 23:41:45 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Retzker",
"A.",
""
],
[
"Plenio",
"M. B.",
""
]
]
|
quant-ph/0607200 | Renato Fedele | Sergio De Nicola, Renato Fedele, Margarita A. Man'ko, Vladimir I.
Man'ko | New uncertainty relations for tomographic entropy: Application to
squeezed states and solitons | 18 pages, 2 figures, to be published in European Physical Journal B | null | 10.1140/epjb/e2006-00280-0 | null | quant-ph | null | Using the tomographic probability distribution (symplectic tomogram)
describing the quantum state (instead of the wave function or density matrix)
and properties of recently introduced tomographic entropy associated with the
probability distribution, the new uncertainty relation for the tomographic
entropy is obtained. Examples of the entropic uncertainty relation for squeezed
states and solitons of the Bose--Einstein condensate are considered.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 07:49:07 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"De Nicola",
"Sergio",
""
],
[
"Fedele",
"Renato",
""
],
[
"Man'ko",
"Margarita A.",
""
],
[
"Man'ko",
"Vladimir I.",
""
]
]
|
quant-ph/0607201 | Bayram Kurucay | Bayram Kurucay | Second Quantization and Bogoliubov Approximation | null | null | null | null | quant-ph | null | Recent experiments with trapped alkali atoms have drawn enormous interest to
the theoretical studies concerning Bose-Einstein condensation. The purpose of
this paper is to review one of the approaches to study bosonic matter at zero
temperature, namely the Bogoliubov approximation. Review of a necessary tool,
the second quantization, will also be made.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 08:55:06 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Kurucay",
"Bayram",
""
]
]
|
quant-ph/0607202 | Jaeweon Lee Dr. | Jae-Weon Lee, Jaewan Kim, Taeseung Choi | Quantum Separability of the vacuum for Scalar Fields with a Boundary | 4 pages, 1 figure, Revtex, minor corrections. submitted to Phy. Rev.
A | Phys.Rev. A74 (2006) 044304 | 10.1103/PhysRevA.74.044304 | null | quant-ph hep-th | null | Using the Green's function approach we investigate separability of the vacuum
state of a massless scalar field with a single Dirichlet boundary. Separability
is demonstrated using the positive partial transpose criterion for effective
two-mode Gaussian states of collective operators. In contrast to the vacuum
energy, entanglement of the vacuum is not modified by the presence of the
boundary.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 09:07:11 GMT"
},
{
"version": "v2",
"created": "Wed, 27 Sep 2006 04:10:51 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Lee",
"Jae-Weon",
""
],
[
"Kim",
"Jaewan",
""
],
[
"Choi",
"Taeseung",
""
]
]
|
quant-ph/0607203 | Silvano Garnerone | S. Garnerone, A. Marzuoli, M. Rasetti | Quantum geometry and quantum algorithms | Submitted to J. Phys. A: Math-Gen, for the special issue ``The
Quantum Universe'' in honor of G. C. Ghirardi | J.Phys.A40:3047-3066,2007 | 10.1088/1751-8113/40/12/S10 | null | quant-ph gr-qc | null | Motivated by algorithmic problems arising in quantum field theories whose
dynamical variables are geometric in nature, we provide a quantum algorithm
that efficiently approximates the colored Jones polynomial. The construction is
based on the complete solution of Chern-Simons topological quantum field theory
and its connection to Wess-Zumino-Witten conformal field theory. The colored
Jones polynomial is expressed as the expectation value of the evolution of the
q-deformed spin-network quantum automaton. A quantum circuit is constructed
capable of simulating the automaton and hence of computing such expectation
value. The latter is efficiently approximated using a standard sampling
procedure in quantum computation.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 09:55:24 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Garnerone",
"S.",
""
],
[
"Marzuoli",
"A.",
""
],
[
"Rasetti",
"M.",
""
]
]
|
quant-ph/0607204 | Julia Kempe | Julia Kempe, Laszlo Pyber and Aner Shalev | Permutation groups, minimal degrees and quantum computing | 28 pages, no figures | null | null | null | quant-ph math.GR | null | We study permutation groups of given minimal degree without the classical
primitivity assumption. We provide sharp upper bounds on the order of a
permutation group of minimal degree m and on the number of its elements of any
given support. These results contribute to the foundations of a non-commutative
coding theory.
A main application of our results concerns the Hidden Subgroup Problem for
the symmetric group in Quantum Computing. We completely characterize the hidden
subgroups of the symmetric group that can be distinguished from identity with
weak Quantum Fourier Sampling, showing these are exactly the subgroups with
bounded minimal degree. This implies that the weak standard method for the
symmetric group has no advantage whatsoever over classical exhaustive search.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 12:44:55 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Kempe",
"Julia",
""
],
[
"Pyber",
"Laszlo",
""
],
[
"Shalev",
"Aner",
""
]
]
|
quant-ph/0607205 | Antoine Heidmann | O. Arcizet (LKB - Jussieu), P. -F. Cohadon (LKB - Jussieu), T. Briant
(LKB - Jussieu), M. Pinard (LKB - Jussieu), A. Heidmann (LKB - Jussieu) | Radiation-pressure cooling and optomechanical instability of a
micro-mirror | null | Nature 444 (2006) 71 | 10.1038/nature05244 | null | quant-ph | null | Recent experimental progress in table-top experiments or gravitational-wave
interferometers has enlightened the unique displacement sensitivity offered by
optical interferometry. As the mirrors move in response to radiation pressure,
higher power operation, though crucial for further sensitivity enhancement,
will however increase quantum effects of radiation pressure, or even jeopardize
the stable operation of the detuned cavities proposed for next-generation
interferometers. The appearance of such optomechanical instabilities is the
result of the nonlinear interplay between the motion of the mirrors and the
optical field dynamics. In a detuned cavity indeed, the displacements of the
mirror are coupled to intensity fluctuations, which modifies the effective
dynamics of the mirror. Such "optical spring" effects have already been
demonstrated on the mechanical damping of an electromagnetic waveguide with a
moving wall, on the resonance frequency of a specially designed flexure
oscillator, and through the optomechanical instability of a silica
micro-toroidal resonator. We present here an experiment where a
micro-mechanical resonator is used as a mirror in a very high-finesse optical
cavity and its displacements monitored with an unprecedented sensitivity. By
detuning the cavity, we have observed a drastic cooling of the micro-resonator
by intracavity radiation pressure, down to an effective temperature of 10 K. We
have also obtained an efficient heating for an opposite detuning, up to the
observation of a radiation-pressure induced instability of the resonator.
Further experimental progress and cryogenic operation may lead to the
experimental observation of the quantum ground state of a mechanical resonator,
either by passive or active cooling techniques.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 14:23:41 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Arcizet",
"O.",
"",
"LKB - Jussieu"
],
[
"Cohadon",
"P. -F.",
"",
"LKB - Jussieu"
],
[
"Briant",
"T.",
"",
"LKB - Jussieu"
],
[
"Pinard",
"M.",
"",
"LKB - Jussieu"
],
[
"Heidmann",
"A.",
"",
"LKB - Jussieu"
]
]
|
quant-ph/0607206 | Sean Barrett | S. D. Barrett, G. J. Milburn | Quantum information processing via a lossy bus | Added more discussion on effects of noise. Typos corrected | Phys. Rev. A 74, 060302(R) (2006) | 10.1103/PhysRevA.74.060302 | null | quant-ph | null | We describe a method to perform two qubit measurements and logic operations
on pairs of qubits which each interact with a harmonic oscillator degree of
freedom (the \emph{bus}), but do not directly interact with one another. Our
scheme uses only weak interactions between the qubit and the bus, homodyne
measurements, and single qubit operations. In contrast to earlier schemes, the
technique presented here is extremely robust to photon loss in the bus mode,
and can function with high fidelity even when the rate of photon loss is
comparable to the strength of the qubit-bus coupling.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 14:46:57 GMT"
},
{
"version": "v2",
"created": "Sun, 7 Jan 2007 12:49:49 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Barrett",
"S. D.",
""
],
[
"Milburn",
"G. J.",
""
]
]
|
quant-ph/0607207 | Rosario Lo Franco | R. Lo Franco, G. Compagno, A. Messina, and A. Napoli | Single-Shot Generation and Detection of a Two-Photon Generalized
Binomial State in a Cavity | 4 pages, 2 figures, submitted to Physical Review Letters | Phys.Rev.A74:045803,2006 | 10.1103/PhysRevA.74.045803 | null | quant-ph | null | A "quasi-deterministic" scheme to generate a two-photon generalized binomial
state in a single-mode high-Q cavity is proposed. We also suggest a single-shot
scheme to measure the generated state based on a probe two-level atom that
"reads" the cavity field. The possibility of implementing the schemes is
discussed.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 15:18:09 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Franco",
"R. Lo",
""
],
[
"Compagno",
"G.",
""
],
[
"Messina",
"A.",
""
],
[
"Napoli",
"A.",
""
]
]
|
quant-ph/0607208 | Jeffrey Tollaksen Dr. | Jeff Tollaksen and Yakir Aharonov | Non-statistical Weak Measurements | null | null | 10.1117/12.719329 | null | quant-ph | null | Non-statistical weak measurements yield weak values that are outside the
range of eigenvalues and are not rare, suggesting that weak values are a
property of every pre-and-post-selected ensemble. They also extend the
applicability and valid regime of weak values.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 17:05:22 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Tollaksen",
"Jeff",
""
],
[
"Aharonov",
"Yakir",
""
]
]
|
quant-ph/0607209 | Paul Slater | Paul B. Slater | Univariate Functions for the Hilbert-Schmidt Volumes of the Real and
Complex Separable Two-Qubit Systems | 14 pages, 6 figures | null | null | null | quant-ph | null | The (complex) two-qubit systems comprise a 15-dimensional convex set and the
real two-qubit systems, a 9-dimensional convex set. While formulas for the
Hilbert-Schmidt volumes of these two sets are known -- owing to recent
important work of Sommers and Zyczkowski (J. Phys. A {36}, 10115 [2003]) --
formulas have not been so far obtained for the volumes of the separable
subsets. We reduce these two problems to the determination of certain functions
of a single variable.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 18:42:33 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Slater",
"Paul B.",
""
]
]
|
quant-ph/0607210 | Beatrix Hiesmayr C. | Beatrix C. Hiesmayr | Nonlocality and entanglement in a strange system | 7 pages, 2 figures, extended version | European Physical Journal C, Vol. 50, 73-79 (2007) | 10.1140/epjc/s10052-006-0199-x | null | quant-ph | null | We show that the relation between nonlocality and entanglement is subtler
than one naively expects. In order to do this we consider the neutral kaon
system--which is oscillating in time (particle--antiparticle mixing) and
decaying--and describe it as an open quantum system. We consider a Bell--CHSH
inequality and show a novel violation for non--maximally entangled states.
Considering the change of purity and entanglement in time we find that, despite
the fact that only two degrees of freedom at a certain time can be measured,
the neutral kaon system does not behave like a bipartite qubit system.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 17:49:23 GMT"
},
{
"version": "v2",
"created": "Tue, 12 Sep 2006 15:55:59 GMT"
},
{
"version": "v3",
"created": "Wed, 13 Sep 2006 07:20:59 GMT"
},
{
"version": "v4",
"created": "Tue, 28 Nov 2006 13:56:19 GMT"
},
{
"version": "v5",
"created": "Thu, 8 Feb 2007 10:26:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Hiesmayr",
"Beatrix C.",
""
]
]
|
quant-ph/0607211 | Ben Reichardt | Rahul Jain, Alexandra Kolla, Gatis Midrijanis, Ben W. Reichardt | On parallel composition of zero-knowledge proofs with black-box quantum
simulators | 18 pages; final version | Quant. Inf. Comp. 9:513-532, 2009 | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Let L be a language decided by a constant-round quantum Arthur-Merlin (QAM)
protocol with negligible soundness error and all but possibly the last message
being classical. We prove that if this protocol is zero knowledge with a
black-box, quantum simulator S, then L in BQP. Our result also applies to any
language having a three-round quantum interactive proof (QIP), with all but
possibly the last message being classical, with negligible soundness error and
a black-box quantum simulator.
These results in particular make it unlikely that certain protocols can be
composed in parallel in order to reduce soundness error, while maintaining zero
knowledge with a black-box quantum simulator. They generalize analogous
classical results of Goldreich and Krawczyk (1990).
Our proof goes via a reduction to quantum black-box search. We show that the
existence of a black-box quantum simulator for such protocols when L notin BQP
would imply an impossibly-good quantum search algorithm.
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 19:19:07 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Dec 2006 22:17:13 GMT"
},
{
"version": "v3",
"created": "Mon, 2 Apr 2007 21:41:28 GMT"
},
{
"version": "v4",
"created": "Sat, 28 Feb 2009 17:33:55 GMT"
}
]
| 2009-06-19T00:00:00 | [
[
"Jain",
"Rahul",
""
],
[
"Kolla",
"Alexandra",
""
],
[
"Midrijanis",
"Gatis",
""
],
[
"Reichardt",
"Ben W.",
""
]
]
|
quant-ph/0607212 | Robert Hadfield | Robert H. Hadfield, Martin J. Stevens, Richard P. Mirin, Sae Woo Nam | Single-photon source characterization with infrared-sensitive
superconducting single-photon detectors | 4 figures | null | 10.1063/1.2717582 | null | quant-ph | null | Single-photon sources and detectors are key enabling technologies in quantum
information processing. Nanowire-based superconducting single-photon detectors
(SSPDs) offer single-photon detection from the visible well into the infrared
with low dark counts, low jitter and short dead times. We report on the high
fidelity characterization (via antibunching and spontaneous emission lifetime
measurements) of a cavity-coupled single-photon source at 902 nm using a pair
of SSPDs. The twin SSPD scheme reported here is well-suited to the
characterization of single-photon sources at telecom wavelengths (1310 nm, 1550
nm).
| [
{
"version": "v1",
"created": "Fri, 28 Jul 2006 22:49:01 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Hadfield",
"Robert H.",
""
],
[
"Stevens",
"Martin J.",
""
],
[
"Mirin",
"Richard P.",
""
],
[
"Nam",
"Sae Woo",
""
]
]
|
quant-ph/0607213 | Ling Zhou | Ling Zhou, Han Xiong, M. Suhail Zubairy | Single-atom as a macroscopic entanglement source | Accepted by Phys. Rev. A | Phys. Rev. A 74, 022321 (2006) | 10.1103/PhysRevA.74.022321 | null | quant-ph | null | We discuss the generation of a macroscopic entangled state in a single atom
cavity-QED system. The three-level atom in a cascade configuration interacts
dispersively with two classical coherent fields inside a doubly resonant
cavity. We show that a macroscopic entangled state between these two cavity
modes can be generated under large detuning conditions. The entanglement
persists even under the presence of cavity losses.
| [
{
"version": "v1",
"created": "Sat, 29 Jul 2006 04:33:35 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Zhou",
"Ling",
""
],
[
"Xiong",
"Han",
""
],
[
"Zubairy",
"M. Suhail",
""
]
]
|
quant-ph/0607214 | Doyeol (David) Ahn | Doyeol Ahn | Hawking effects on the entanglement near the Schwarzschild black hole | Journal of Korean Physical Society, accepted for publication | J.Korean Phys.Soc.50:368-372,2007 | 10.3938/jkps.50.368 | null | quant-ph | null | Hawking radiation effects on an entangled pair near the event horizon of a
Schwarzschild black hole are investigated. The Hawking radiation was found to
degrade both the quantum coherence of the entangled state and the mutual
correlations of the entangled pair. When the black hole evaporated completely,
the measure of entanglement vanished, but the classical correlation between the
entangled pair still remained.
| [
{
"version": "v1",
"created": "Sat, 29 Jul 2006 08:07:21 GMT"
},
{
"version": "v2",
"created": "Wed, 31 Jan 2007 02:43:30 GMT"
}
]
| 2011-08-04T00:00:00 | [
[
"Ahn",
"Doyeol",
""
]
]
|
quant-ph/0607215 | Alexandre Dodonov V | A. V. Dodonov, S. S. Mizrahi, and V. V. Dodonov | Inclusion of non-idealities in the continuous photodetection model | null | Physical Review A 75, 013806 (2007) | 10.1103/PhysRevA.75.013806 | null | quant-ph | null | Some non-ideal effects as non-unit quantum efficiency, dark counts, dead time
and cavity losses that occur in experiments are incorporated within the
continuous photodetection model by using the analytical quantum trajectories
approach. We show that in standard photocounting experiments the validity of
the model can be verified, and the formal expression for the quantum jump
superoperator can also be checked.
| [
{
"version": "v1",
"created": "Sat, 29 Jul 2006 18:08:57 GMT"
},
{
"version": "v2",
"created": "Sat, 28 Oct 2006 14:57:25 GMT"
},
{
"version": "v3",
"created": "Fri, 2 Feb 2007 03:16:09 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Dodonov",
"A. V.",
""
],
[
"Mizrahi",
"S. S.",
""
],
[
"Dodonov",
"V. V.",
""
]
]
|
quant-ph/0607216 | Arleta Szkola | Michael Nussbaum, Arleta Szko{\l}a | The Chernoff lower bound for symmetric quantum hypothesis testing | Published in at http://dx.doi.org/10.1214/08-AOS593 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org) | Annals of Statistics 2009, Vol. 37, No. 2, 1040-1057 | 10.1214/08-AOS593 | IMS-AOS-AOS593 | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider symmetric hypothesis testing in quantum statistics, where the
hypotheses are density operators on a finite-dimensional complex Hilbert space,
representing states of a finite quantum system. We prove a lower bound on the
asymptotic rate exponents of Bayesian error probabilities. The bound represents
a quantum extension of the Chernoff bound, which gives the best asymptotically
achievable error exponent in classical discrimination between two probability
measures on a finite set. In our framework, the classical result is reproduced
if the two hypothetic density operators commute. Recently, it has been shown
elsewhere [Phys. Rev. Lett. 98 (2007) 160504] that the lower bound is
achievable also in the generic quantum (noncommutative) case. This implies that
our result is one part of the definitive quantum Chernoff bound.
| [
{
"version": "v1",
"created": "Sun, 30 Jul 2006 15:04:23 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Apr 2009 05:58:24 GMT"
}
]
| 2009-04-30T00:00:00 | [
[
"Nussbaum",
"Michael",
""
],
[
"Szkoła",
"Arleta",
""
]
]
|
quant-ph/0607217 | Kilian Singer | Stephan Schulz, Ulrich Poschinger, Kilian Singer, Ferdinand
Schmidt-Kaler | Optimization of segmented linear Paul traps and transport of stored
particles | null | Fortschr. Phys. 54, No. 8-10, 648-665 (2006) | 10.1002/prop.200610324 | null | quant-ph | null | Single ions held in linear Paul traps are promising candidates for a future
quantum computer. Here, we discuss a two-layer microstructured segmented linear
ion trap. The radial and axial potentials are obtained from numeric field
simulations and the geometry of the trap is optimized. As the trap electrodes
are segmented in the axial direction, the trap allows the transport of ions
between different spatial regions. Starting with realistic numerically obtained
axial potentials, we optimize the transport of an ion such that the motional
degrees of freedom are not excited, even though the transport speed far exceeds
the adiabatic regime. In our optimization we achieve a transport within roughly
two oscillation periods in the axial trap potential compared to typical
adiabatic transports that take of the order 100 oscillations. Furthermore
heating due to quantum mechanical effects is estimated and suppression
strategies are proposed.
| [
{
"version": "v1",
"created": "Sun, 30 Jul 2006 17:21:54 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Schulz",
"Stephan",
""
],
[
"Poschinger",
"Ulrich",
""
],
[
"Singer",
"Kilian",
""
],
[
"Schmidt-Kaler",
"Ferdinand",
""
]
]
|
quant-ph/0607218 | Caroline Champenois | Caroline Champenois (PIIM), Giovanna Morigi (GRUP D'OPTICA), Juergen
Eschner (ICFO) | Quantum coherence and population trapping in three-photon processes | null | Physical Review A 74 (2006) 053404 | 10.1103/PhysRevA.74.053404 | null | quant-ph | null | The spectroscopic properties of a single, tightly trapped atom are studied,
when the electronic levels are coupled by three laser fields in an $N$-shaped
configuration of levels, whereby a $\Lambda$-type level system is weakly
coupled to a metastable state. We show that depending on the laser frequencies
the response can be tuned from coherent population trapping at two-photon
resonance to novel behaviour at three photon resonance, where the metastable
state can get almost unit occupation in a wide range of parameters. For certain
parameter regimes the system switches spontaneously between dissipative and
coherent dynamics over long time scales.
| [
{
"version": "v1",
"created": "Sun, 30 Jul 2006 17:52:26 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Sep 2006 08:40:11 GMT"
}
]
| 2014-04-16T00:00:00 | [
[
"Champenois",
"Caroline",
"",
"PIIM"
],
[
"Morigi",
"Giovanna",
"",
"GRUP D'OPTICA"
],
[
"Eschner",
"Juergen",
"",
"ICFO"
]
]
|
quant-ph/0607219 | Roberto Floreanini | F. Benatti, R. Floreanini and S. Breteaux | Slipped non-Positive Reduced Dynamics and Entanglement | 23 pages, 7 figures, LaTex | null | 10.1134/S1054660X06100021 | null | quant-ph cond-mat.other hep-th | null | Non-positive Markov approximations are sometimes used to describe the
dynamics of qubits in weak interaction with suitable environments; the
appearance of negative probabilities is avoided by assuming that the transient
regime eliminates from the possible initial conditions those qubit states which
would otherwise be mapped out of the Bloch sphere by the subsequent Markovian
time-evolution. By means of a simple model, we discuss some physical
inconsistencies of this approach in relation to entanglement; in particular, we
show that slipped non-positive reduced dynamics might create entanglement
through a purely local action.
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 09:42:00 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Benatti",
"F.",
""
],
[
"Floreanini",
"R.",
""
],
[
"Breteaux",
"S.",
""
]
]
|
quant-ph/0607220 | J Banerji | G. S. Agarwal and J. Banerji | Entanglement by linear SU(2) transformations: generation and evolution
of quantum vortex states | 6 figures | null | 10.1088/0305-4470/39/37/011 | null | quant-ph | null | We consider the evolution of a two-mode system of bosons under the action of
a Hamiltonian that generates linear SU(2) transformations. The Hamiltonian is
generic in that it represents a host of entanglement mechanisms, which can thus
be treated in a unified way. We start by solving the quantum dynamics
analytically when the system is initially in a Fock state. We show how the two
modes get entangled by evolution to produce a coherent superposition of vortex
states in general, and a single vortex state under certain conditions. The
degree of entanglement between the modes is measured by finding the explicit
analytical dependence of the Von Neumann entropy on the system parameters. The
reduced state of each mode is analyzed by means of its correlation function and
spatial coherence function. Remarkably, our analysis is shown to be equally as
valid for a variety of initial states that can be prepared from a two-mode Fock
state via a unitary transformation and for which the results can be obtained by
mere inspection of the corresponding results for an initial Fock state. As an
example, we consider a quantum vortex as the initial state and also find
conditions for its revival and charge conjugation. While studying the evolution
of the initial vortex state, we have encountered and explained an interesting
situation in which the entropy of the system does not evolve whereas its wave
function does. Although the modal concept has been used throughout the paper,
it is important to note that the theory is equally applicable for a
two-particle system in which each particle is represented by its bosonic
creation and annihilation operators.
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 16:43:29 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Agarwal",
"G. S.",
""
],
[
"Banerji",
"J.",
""
]
]
|
quant-ph/0607221 | Dmitry Garanin | R. Schilling, Mark Vogelsberger, and D. A. Garanin | Nonadiabatic Transitions for a Decaying Two-Level-System: Geometrical
and Dynamical Contributions | 12 PR pages, 8 figures | null | 10.1088/0305-4470/39/44/008 | null | quant-ph | null | We study the Landau-Zener Problem for a decaying two-level-system described
by a non-hermitean Hamiltonian, depending analytically on time. Use of a
super-adiabatic basis allows to calculate the non-adiabatic transition
probability P in the slow-sweep limit, without specifying the Hamiltonian
explicitly. It is found that P consists of a ``dynamical'' and a
``geometrical'' factors. The former is determined by the complex adiabatic
eigenvalues E_(t), only, whereas the latter solely requires the knowledge of
\alpha_(+-)(t), the ratio of the components of each of the adiabatic
eigenstates. Both factors can be split into a universal one, depending only on
the complex level crossing points, and a nonuniversal one, involving the full
time dependence of E_(+-)(t). This general result is applied to the
Akulin-Schleich model where the initial upper level is damped with damping
constant $\gamma$. For analytic power-law sweeps we find that Stueckelberg
oscillations of P exist for gamma smaller than a critical value gamma_c and
disappear for gamma > gamma_c. A physical interpretation of this behavior will
be presented by use of a damped harmonic oscillator.
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 14:18:48 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Schilling",
"R.",
""
],
[
"Vogelsberger",
"Mark",
""
],
[
"Garanin",
"D. A.",
""
]
]
|
quant-ph/0607222 | Rajesh R. Parwani | R.Parwani and G.Tabia | Universality in an Information-theoretic Motivated Nonlinear Schrodinger
Equation | Final Journal Version; 23 pages inclusive of 3 figures | J.Phys.A40:5621-5636,2007 | 10.1088/1751-8113/40/21/012 | null | quant-ph hep-th nlin.PS | null | Using perturbative methods, we analyse a nonlinear generalisation of
Schrodinger's equation that had previously been obtained through
information-theoretic arguments. We obtain analytical expressions for the
leading correction, in terms of the nonlinearity scale, to the energy
eigenvalues of the linear Schrodinger equation in the presence of an external
potential and observe some generic features. In one space dimension these are:
(i) For nodeless ground states, the energy shifts are subleading in the
nonlinearity parameter compared to the shifts for the excited states, (ii) the
shifts for the excited states are due predominantly to contribution from the
nodes of the unperturbed wavefunctions and (iii) the energy shifts for excited
states are positive for small values of a regulating parameter and negative at
large values, vanishing at a universal critical value that is not manifest in
the equation. Some of these features hold true for higher dimensional problems.
We also study two exactly solved nonlinear Schrodinger equations so as to
contrast our observations. Finally, we comment on the possible significance of
our results if the nonlinearity is physically realised.
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 14:26:20 GMT"
},
{
"version": "v2",
"created": "Thu, 24 May 2007 07:42:06 GMT"
}
]
| 2008-11-26T00:00:00 | [
[
"Parwani",
"R.",
""
],
[
"Tabia",
"G.",
""
]
]
|
quant-ph/0607223 | Nagalakshmi Rao A | Nagalakshmi A Rao, B. A. Kagali | Klein paradox for bound states - A puzzling phenomenon | 6 pages | Mapana, MUS Vol.5(2) 2006, 14 - 18 | null | null | quant-ph | null | While Klein paradox is often encountered in the context of scattering of
relativistic particles at a potential barrier, we presently discuss a puzzling
situation that arises with the Klein-Gordon equation for bound states. With the
usual minimal coupling procedure of introducing the interaction potential, a
paradoxical situation arises when the 'hill' becomes a 'well', simulating a
bound-state like situation. The phenomenal phenomenon for bound states is
contrary to the conventional wisdom of quantum mechanics and is analogous to
the well-known Klein paradox, a generic property of relativistic wave
equations.
PACs Nos. 03.65.Ge, 03.65.Pm
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 17:58:41 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Rao",
"Nagalakshmi A",
""
],
[
"Kagali",
"B. A.",
""
]
]
|
quant-ph/0607224 | M. O. Terra Cunha | Marcelo O Terra Cunha and Vlatko Vedral | How to Extract Entanglement from a Piece of Solid or a Bunch of Neutrons | Prepared for the Proceedings of Central European Workshop on Quantum
Optics, Vienna - 2006 | Acta Physica Hungarica A 26, 261-268 (2006) | 10.1556/APH.26.2006.3-4.6 | null | quant-ph | null | We review how to obtain spin entangled pairs of fermions from a Fermi gas. An
experiment with neutrons is proposed in order to get such pairs.
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 18:06:25 GMT"
}
]
| 2007-06-13T00:00:00 | [
[
"Cunha",
"Marcelo O Terra",
""
],
[
"Vedral",
"Vlatko",
""
]
]
|
quant-ph/0608001 | Xiongfeng Ma | Xiongfeng Ma | Unconditional security at a low cost | Accepted by International Conference on Quantum Foundation and
Technology: Frontier and Future 2006 (ICQFT'06) | PHYSICAL REVIEW A 74, 052325 (2006) | 10.1103/PhysRevA.74.052325 | null | quant-ph | null | By simulating four quantum key distribution (QKD) experiments and analyzing
one decoy-state QKD experiment, we compare two data post-processing schemes
based on security against individual attack by L\"{u}tkenhaus, and
unconditional security analysis by Gottesman-Lo-L\"{u}tkenhaus-Preskill. Our
results show that these two schemes yield close performances. Since the Holy
Grail of QKD is its unconditional security, we conclude that one is better off
considering unconditional security, rather than restricting to individual
attacks.
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 20:29:09 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Ma",
"Xiongfeng",
""
]
]
|
quant-ph/0608002 | Jose Lunardi | C.A. Bonin, J.T. Lunardi, L.A. Manzoni, and B.M. Pimentel | Relation between quantum tunneling times for bosons | null | null | null | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This paper has been withdrawn by the authors
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 20:57:37 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Aug 2006 12:03:03 GMT"
},
{
"version": "v3",
"created": "Fri, 15 Aug 2008 01:38:16 GMT"
}
]
| 2008-08-15T00:00:00 | [
[
"Bonin",
"C. A.",
""
],
[
"Lunardi",
"J. T.",
""
],
[
"Manzoni",
"L. A.",
""
],
[
"Pimentel",
"B. M.",
""
]
]
|
quant-ph/0608003 | Masanori Sato | Masanori Sato | Proposed experiment to test the non-locality hypothesis in transient
light-interference phenomena | 10 pages, 7 figures | Annales de la Foundation Lois de Broglie, 33, 307, (2008) | null | null | quant-ph | null | The transient phenomena of the Mach-Zender interferometer are discussed. To
test the non-locality hypothesis, a single mode laser with a large coherence
length is used. The behavior of a photon and its wave packets in the paths of
the interferometer are discussed. Coherent photons have wave packets that
overlap, thus their interference pattern is influenced by the overlap of the
wave packets of other photons in transient phenomena. The proposed transient
light-interference experiment will provide experimental data testing the
non-locality hypothesis.
| [
{
"version": "v1",
"created": "Mon, 31 Jul 2006 23:49:26 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Sep 2006 02:21:16 GMT"
},
{
"version": "v3",
"created": "Tue, 8 May 2007 03:58:09 GMT"
},
{
"version": "v4",
"created": "Tue, 7 Aug 2007 01:38:21 GMT"
},
{
"version": "v5",
"created": "Tue, 20 May 2008 04:04:25 GMT"
}
]
| 2009-05-14T00:00:00 | [
[
"Sato",
"Masanori",
""
]
]
|
quant-ph/0608004 | Ian Durham | Ian T. Durham | Limitations on entropic Bell inequalities | 4 pages | null | null | null | quant-ph | null | The derivation of Bell inequalities in terms of quantum statistical
(thermodynamic) entropies is considered. Inequalities of the Wigner form are
derived but shown to be extremely limiting in their applicability due to the
nature of the density matrices involved. This also helps to identify a
limitation in the Cerf-Adami inequalities.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 01:15:08 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Durham",
"Ian T.",
""
]
]
|
quant-ph/0608005 | Holger F. Hofmann | Holger F. Hofmann, Ryo Okamoto, Shigeki Takeuchi | Analysis of an experimental quantum logic gate by complementary
classical operations | 14 pages, 1 figure, 3 tables, Brief Review for Modern Physics Letters
A, includes a more detailed analysis of the experimental data in Phys. Rev.
Lett. 95, 210506 (2005) (quant-ph/0506263). v2 has minor corrections in
layout | Mod. Phys. Lett. A 21, 1837 (2006) | 10.1142/S0217732306021281 | null | quant-ph | null | Quantum logic gates can perform calculations much more efficiently than their
classical counterparts. However, the level of control needed to obtain a
reliable quantum operation is correspondingly higher. In order to evaluate the
performance of experimental quantum gates, it is therefore necessary to
identify the essential features that indicate quantum coherent operation. In
this paper, we show that an efficient characterization of an experimental
device can be obtained by investigating the classical logic operations on a
pair of complementary basis sets. It is then possible to obtain reliable
predictions about the quantum coherent operations of the gate such as
entanglement generation and Bell state discrimination even without performing
these operations directly.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 01:40:39 GMT"
},
{
"version": "v2",
"created": "Tue, 31 Oct 2006 23:45:05 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Hofmann",
"Holger F.",
""
],
[
"Okamoto",
"Ryo",
""
],
[
"Takeuchi",
"Shigeki",
""
]
]
|
quant-ph/0608006 | Magdalena Stobi\'nska | Magdalena Stobi\'nska and Krzysztof W\'odkiewicz | Witnessing Entanglement with Second-Order Interference and Stokes
Parameters | 10 pages, 2 figure | Acta Physica Hungarica A 26, 301 (2006) | 10.1556/APH.26.2006.3-4.10 | null | quant-ph | null | We propose to use Stokes parameter as an entanglement witness for correlated
EPR mixed states of light. Such states can be generated with a beam splitter
acting on two mixed squeezed states of light. Stokes witness operators are
closely related to the Hanbury-Brown and Twiss interference and can be used to
test entanglement in balanced homodyne experiments involving fluctuations of
quantum quadratures of the electric field.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 07:29:30 GMT"
}
]
| 2010-05-04T00:00:00 | [
[
"Stobińska",
"Magdalena",
""
],
[
"Wódkiewicz",
"Krzysztof",
""
]
]
|
quant-ph/0608007 | Giulio Chiribella | G. Chiribella and G. M. D'Ariano | Quantum information becomes classical when distributed to many users | 4 pages, no figures, published version | Phys. Rev. Lett. 97, 250503 (2006) | 10.1103/PhysRevLett.97.250503 | null | quant-ph | null | Any physical transformation that equally distributes quantum information over
a large number M of users can be approximated by a classical broadcasting of
measurement outcomes. The accuracy of the approximation is at least of the
order 1/M. In particular, quantum cloning of pure and mixed states can be
approximated via quantum state estimation. As an example, for optimal qubit
cloning with 10 output copies, a single user has error probability p > 0.45 in
distinguishing classical from quantum output--a value close to the error
probability of the random guess.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 10:56:52 GMT"
},
{
"version": "v2",
"created": "Thu, 10 Aug 2006 17:43:50 GMT"
},
{
"version": "v3",
"created": "Wed, 31 Jan 2007 16:04:29 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Chiribella",
"G.",
""
],
[
"D'Ariano",
"G. M.",
""
]
]
|
quant-ph/0608008 | Charles Tresser | Charles Tresser | A Bell Theorem with no locality assumption | Replaces with essential changes quant-ph/0501030 that is not removed
or replaced in quant-ph because it is quite different | null | null | null | quant-ph | null | We prove here a version of Bell Theorem that does not assume locality. As a
consequence classical realism, and not locality, is the common source of the
violation by nature of all Bell Inequalities.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 10:58:10 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Oct 2006 10:34:06 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Tresser",
"Charles",
""
]
]
|
quant-ph/0608009 | Ivan Marcikic | Hou Shun Poh, Chune Yang Lum, Ivan Marcikic, Antia Lamas-Linares, and
Christian Kurtsiefer | Joint Spectrum Mapping of Polarization Entanglement in Spontaneous
Parametric Down-conversion | 8 pages, 7 figures, submitted | Phys. Rev. A 75, 043816 (2007) | 10.1103/PhysRevA.75.043816 | null | quant-ph | null | Polarization-entangled photon pairs can be efficiently prepared into pure
Bell states with a high fidelity via type-II spontaneous parametric
down-conversion (SPDC) of narrow-band pump light. However, the use of
femtosecond pump pulses to generate multi-photon states with precise timing
often requires spectral filtering to maintain a high quality of polarization
entanglement. This typically reduces the efficiency of photon pair collection.
We experimentally map the polarization correlations of photon pairs from such a
source over a range of down-converted wavelengths with a high spectral
resolution and find strong polarization correlations everywhere. A spectrally
dependent imbalance between contributions from the two possible decay paths of
SPDC is identified as the reason for a reduction in entanglement quality
observed with femtosecond pump pulses. Our spectral measurements allow to
predict the polarization correlations for arbitrary filter profiles when the
frequency degree of freedom of the photon pairs is ignored.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 11:32:35 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Poh",
"Hou Shun",
""
],
[
"Lum",
"Chune Yang",
""
],
[
"Marcikic",
"Ivan",
""
],
[
"Lamas-Linares",
"Antia",
""
],
[
"Kurtsiefer",
"Christian",
""
]
]
|
quant-ph/0608010 | Motohisa Fukuda | Motohisa Fukuda | Simplification of additivity conjecture in quantum information theory | 8 pages | Quantum Information Processing, Vol. 6, 179-186, (2007) | 10.1007/s11128-007-0051-8 | null | quant-ph | null | We simplify some conjectures in quantum information theory; the additivity of
minimal output entropy, the multiplicativity of maximal output p-norm and the
superadditivity of convex closure of output entropy. We construct a unital
channel for a given channel so that they share the above additivity properties;
we can reduce the conjectures for all channels to those for unital channels.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 11:18:57 GMT"
},
{
"version": "v2",
"created": "Mon, 9 Apr 2007 18:14:06 GMT"
}
]
| 2007-08-21T00:00:00 | [
[
"Fukuda",
"Motohisa",
""
]
]
|
quant-ph/0608011 | Michele Caponigro | Michele Caponigro, Helen Lynn | Questions and Physical Reality -Simple Philosophical considerations- | 3 pages | null | null | null | quant-ph | null | We argue, through some philosophical considerations, on (i)dependent or (ii)
an independent existence of physical reality underlying quantum states.
According these simple considerations, we conclude that is impossible to have a
clear independent existence of physical reality, we need to search the reasons
in the relationship between our questions (the observers) and the consequent
answers (always estimated by the same observers). Finally, we infer that every
theory is affected by our "questions", so we cannot speak about an
unconditional and independent theory underlying physical reality. Plan of the
paper. The existence of physical reality underlying quantum states: (i) it
before bit,(ii)it without bit,(iii)it from bit.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 13:11:51 GMT"
}
]
| 2007-05-23T00:00:00 | [
[
"Caponigro",
"Michele",
""
],
[
"Lynn",
"Helen",
""
]
]
|
quant-ph/0608012 | Leandro Aolita | Leandro Aolita and Florian Mintert | Measuring Multipartite Concurrence with a Single Factorizable Observable | 4 pages; no figures; published version | Phys. Rev. Lett. 97, 050501 (2006) | 10.1103/PhysRevLett.97.050501 | null | quant-ph | null | We show that, for any composite system with an arbitrary number of
finite-dimensional subsystems, it is possible to directly measure the
multipartite concurrence of pure states by detecting only one single
factorizable observable, provided that two copies of the composite state are
available. This result can be immediately put into practice in trapped-ion and
entangled-photon experiments.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 14:21:50 GMT"
},
{
"version": "v2",
"created": "Wed, 24 Oct 2007 03:22:13 GMT"
}
]
| 2009-11-13T00:00:00 | [
[
"Aolita",
"Leandro",
""
],
[
"Mintert",
"Florian",
""
]
]
|
quant-ph/0608013 | Roman Orus | Roman Orus | Entanglement, quantum phase transitions and quantum algorithms | PhD Thesis, July 2006, University of Barcelona, 162 pages, compressed
figures | null | null | null | quant-ph cond-mat.str-el hep-th | null | The work that we present in this thesis tries to be at the crossover of
quantum information science, quantum many-body physics, and quantum field
theory. We use tools from these three fields to analyze problems that arise in
the interdisciplinary intersection. More concretely, in Chapter 1 we consider
the irreversibility of renormalization group flows from a quantum information
perspective by using majorization theory and conformal field theory. In Chapter
2 we compute the entanglement of a single copy of a bipartite quantum system
for a variety of models by using techniques from conformal field theory and
Toeplitz matrices. The entanglement entropy of the so-called
Lipkin-Meshkov-Glick model is computed in Chapter 3, showing analogies with
that of (1+1)-dimensional quantum systems. In Chapter 4 we apply the ideas of
scaling of quantum correlations in quantum phase transitions to the study of
quantum algorithms, focusing on Shor's factorization algorithm and quantum
algorithms by adiabatic evolution solving an NP-complete and the searching
problems. Also, in Chapter 5 we use techniques originally inspired by
condensed-matter physics to develop classical simulations, using the so-called
matrix product states, of an adiabatic quantum algorithm. Finally, in Chapter 6
we consider the behavior of some families of quantum algorithms from the
perspective of majorization theory. The structure within each Chapter is such
that the last section always summarizes the basic results. Some general
conclusions and possible future directions are briefly discussed in Chapter 7.
Appendix A, Appendix B and Appendix C respectively deal with some basic notions
on majorization theory, conformal field theory, and classical complexity
theory.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 15:50:13 GMT"
}
]
| 2009-09-29T00:00:00 | [
[
"Orus",
"Roman",
""
]
]
|
quant-ph/0608014 | Andreas Winter | Manuel A. Ballester, Stephanie Wehner, Andreas Winter | State Discrimination with Post-Measurement Information | twentynine pages, no figures, equations galore. v2 thirtyone pages,
one new result w.r.t. v1 | IEEE Trans. on Information Theory, vol 54, issue 9 (2008), pages
4183 - 4198 | 10.1109/TIT.2008.928276 | null | quant-ph | null | We introduce a new state discrimination problem in which we are given
additional information about the state after the measurement, or more
generally, after a quantum memory bound applies. In particular, the following
special case plays an important role in quantum cryptographic protocols in the
bounded storage model: Given a string x encoded in an unknown basis chosen from
a set of mutually unbiased bases, you may perform any measurement, but then
store at most q qubits of quantum information. Later on, you learn which basis
was used. How well can you compute a function f(x) of x, given the initial
measurement outcome, the q qubits and the additional basis information? We
first show a lower bound on the success probability for any balanced function,
and any number of mutually unbiased bases, beating the naive strategy of simply
guessing the basis. We then show that for two bases, any Boolean function f(x)
can be computed perfectly if you are allowed to store just a single qubit,
independent of the number of possible input strings x. However, we show how to
construct three bases, such that you need to store all qubits in order to
compute f(x) perfectly. We then investigate how much advantage the additional
basis information can give for a Boolean function. To this end, we prove
optimal bounds for the success probability for the AND and the XOR function for
up to three mutually unbiased bases. Our result shows that the gap in success
probability can be maximal: without the basis information, you can never do
better than guessing the basis, but with this information, you can compute f(x)
perfectly. We also exhibit an example where the extra information does not give
any advantage at all.
| [
{
"version": "v1",
"created": "Tue, 1 Aug 2006 17:04:02 GMT"
},
{
"version": "v2",
"created": "Tue, 5 Sep 2006 16:03:29 GMT"
}
]
| 2009-01-20T00:00:00 | [
[
"Ballester",
"Manuel A.",
""
],
[
"Wehner",
"Stephanie",
""
],
[
"Winter",
"Andreas",
""
]
]
|
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